1
|
DiBello M, Healy AR, Nikolayevskiy H, Xu Z, Herzon SB. Structure Elucidation of Secondary Metabolites: Current Frontiers and Lingering Pitfalls. Acc Chem Res 2023; 56:1656-1668. [PMID: 37220079 PMCID: PMC10468810 DOI: 10.1021/acs.accounts.3c00183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Analytical methods allow for the structure determination of submilligram quantities of complex secondary metabolites. This has been driven in large part by advances in NMR spectroscopic capabilities, including access to high-field magnets equipped with cryogenic probes. Experimental NMR spectroscopy may now be complemented by remarkably accurate carbon-13 NMR calculations using state-of-the-art DFT software packages. Additionally, microED analysis stands to have a profound effect on structure elucidation by providing X-ray-like images of microcrystalline samples of analytes. Nonetheless, lingering pitfalls in structure elucidation remain, particularly for isolates that are unstable or highly oxidized. In this Account, we discuss three projects from our laboratory that highlight nonoverlapping challenges to the field, with implications for chemical, synthetic, and mechanism of action studies. We first discuss the lomaiviticins, complex unsaturated polyketide natural products disclosed in 2001. The original structures were derived from NMR, HRMS, UV-vis, and IR analysis. Owing to the synthetic challenges presented by their structures and the absence of X-ray crystallographic data, the structure assignments remained untested for nearly two decades. In 2021, the Nelson group at Caltech carried out microED analysis of (-)-lomaiviticin C, leading to the startling discovery that the original structure assignment of the lomaiviticins was incorrect. Acquisition of higher-field (800 MHz 1H, cold probe) NMR data as well as DFT calculations provided insights into the basis for the original misassignment and lent further support to the new structure identified by microED. Reanalysis of the 2001 data set reveals that the two structure assignments are nearly indistinguishable, underscoring the limitations of NMR-based characterization. We then discuss the structure elucidation of colibactin, a complex, nonisolable microbiome metabolite implicated in colorectal cancer. The colibactin biosynthetic gene cluster was detected in 2006, but owing to colibactin's instability and low levels of production, it could not be isolated or characterized. We used a combination of chemical synthesis, mechanism of action studies, and biosynthetic analysis to identify the substructures in colibactin. These studies, coupled with isotope labeling and tandem MS analysis of colibactin-derived DNA interstrand cross-links, ultimately led to a structure assignment for the metabolite. We then discuss the ocimicides, plant secondary metabolites that were studied as agents against drug-resistant P. falciparum. We synthesized the core structure of the ocimicides and found significant discrepancies between our experimental NMR spectroscopic data and that reported for the natural products. We determined the theoretical carbon-13 NMR shifts for 32 diastereomers of the ocimicides. These studies indicated that a revision of the connectivity of the metabolites is likely needed. We end with some thoughts on the frontiers of secondary metabolite structure determination. As modern NMR computational methods are straightforward to execute, we advocate for their systematic use in validating the assignments of novel secondary metabolites.
Collapse
Affiliation(s)
- Mikaela DiBello
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Alan R Healy
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Herman Nikolayevskiy
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Zhi Xu
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Seth B Herzon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
- Departments of Pharmacology and Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut 06520, United States
| |
Collapse
|
2
|
Dunås P, Paterson AJ, Kociok-Köhn G, Rahm M, Lewis SE, Kann N. Palladium-catalyzed stereoselective domino arylation-acylation: an entry to chiral tetrahydrofluorenone scaffolds. Chem Commun (Camb) 2021; 57:6518-6521. [PMID: 34105551 DOI: 10.1039/d1cc02160e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A palladium-catalyzed domino arylation-cyclization of biocatalytically derived cyclic 1,3-dienes is demonstrated. The reaction introduces a high degree of structural complexity in a single step, giving access to tricyclic tetrahydrofluorenones with full regio- and stereoselectivity. The transformation proceeds through a novel acylation-terminated Heck-type sequence, and quantum chemical calculations indicate that C-H activation is involved in the terminating acylation step.
Collapse
Affiliation(s)
- Petter Dunås
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
| | - Andrew J Paterson
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
| | - Gabriele Kociok-Köhn
- Materials and Chemical Characterization Facility, Convocation Avenue, University of Bath, Bath, BA2 7AY, UK
| | - Martin Rahm
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
| | - Simon E Lewis
- Centre for Sustainable Circular Technologies, Convocation Avenue, University of Bath, Bath, BA2 7AY, UK. and Department of Chemistry, Convocation Avenue, University of Bath, Bath, BA2 7AY, UK
| | - Nina Kann
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
| |
Collapse
|
3
|
Hsu IT, Tomanik M, Herzon SB. Metric-Based Analysis of Convergence in Complex Molecule Synthesis. Acc Chem Res 2021; 54:903-916. [PMID: 33523640 DOI: 10.1021/acs.accounts.0c00817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Convergent syntheses are characterized by the coupling of two or more synthetic intermediates of similar complexity, often late in a pathway. At its limit, a fully convergent synthesis is achieved when commercial or otherwise readily available intermediates are coupled to form the final target in a single step. Of course, in all but exceptional circumstances this level of convergence is purely hypothetical; in practice, additional steps are typically required to progress from fragment coupling to the target. Additionally, the length of the sequence required to access each target is a primary consideration in synthetic design.In this Account, we provide an overview of alkaloid, polyketide, and diterpene metabolites synthesized in our laboratory and present parameters that may be used to put the degree of convergence of each synthesis on quantitative footing. We begin with our syntheses of the antiproliferative, antimicrobial bacterial metabolite (-)-kinamycin F (1) and related dimeric structure (-)-lomaiviticin aglycon (2). These synthetic routes featured a three-step sequence to construct a complex diazocyclopentadiene found in both targets and an oxidative dimerization to unite the two halves of (-)-lomaiviticin aglycon (2). We then follow with our synthesis of the antineurodegenerative alkaloid (-)-huperzine A (3). Our route to (-)-huperzine A (3) employed a diastereoselective three-component coupling reaction, followed by the intramolecular α-arylation of a β-ketonitrile intermediate, to form the carbon skeleton of the target. We then present our syntheses of the hasubanan alkaloids (-)-hasubanonine (4), (-)-delavayine (5), (-)-runanine (6), (+)-periglaucine B (7), and (-)-acutumine (8). These alkaloids bear a 7-azatricyclo[4.3.3.01,6]dodecane (propellane) core and a highly oxidized cyclohexenone ring. The propellane structure was assembled by the addition of an aryl acetylide to a complex iminium ion, followed by intramolecular 1,4-addition. We then present our synthesis of the guanidinium alkaloid (+)-batzelladine B (9), which contains two complex polycyclic guanidine residues united by an ester linkage. This target was logically disconnected by an esterification to allow for the independent synthesis of each guanidine residue. A carefully orchestrated cascade reaction provided (+)-batzelladine B (9) in a single step following fragment coupling by esterification. We then discuss our synthesis of the diterpene fungal metabolite (+)-pleuromutilin (10). The synthesis of (+)-pleuromutilin (10) proceeded via a fragment coupling involving two neopentylic reagents and employed a nickel-catalyzed reductive cyclization reaction to close the eight-membered ring, ultimately providing access to (+)-pleuromutilin (10), (+)-12-epi-pleuromutilin (11), and (+)-12-epi-mutilin (12). Finally, we discuss our synthesis of (-)-myrocin G (13), a tricyclic pimarane diterpene that was assembled by a convergent annulation.In the final section of this Account, we present several paramaters to analyze and quantitatively assess the degree of convergence of each synthesis. These parameters include: (1) the number of steps required following the point of convergence, (2) the difference in the number of steps required to prepare each coupling partner, (3) the percentage of carbons (or, more broadly, atoms) present at the point of convergence, and (4) the complexity generated in the fragment coupling step. While not an exhaustive list, these parameters bring the strengths and weaknesses each synthetic strategy to light, emphasizing the key contributors to the degree of convergence of each route while also highlighting the nuances of these analyses.
Collapse
Affiliation(s)
- Ian Tingyung Hsu
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Martin Tomanik
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Seth B. Herzon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
- Department of Pharmacology, Yale School of Medicine, New Haven, Connecticut 06520, United States
| |
Collapse
|
4
|
Mikhaylov AA, Ikonnikova VA, Solyev PN. Disclosing biosynthetic connections and functions of atypical angucyclinones with a fragmented C-ring. Nat Prod Rep 2021; 38:1506-1517. [PMID: 33480893 DOI: 10.1039/d0np00082e] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This review on atypical angucyclinones possessing an aromatic cleavage of the C-ring covers literature between 1995 and early 2020.The unusual framework of the middle C-ring, "broken" as a result of biotransformations and oxidations in vivo and bearing an sp3-C connection, is of interest for biosynthetic investigations. The reported 39 natural compounds (55 including stereoisomers) have been analyzed and arranged into three structural groups. The biosynthetic origin of all these compounds has been thoroughly reviewed and revised, based on the found connections with oxidized angucyclinone structures. The data on biological activities has been summarized. Careful consideration of the origin of the structure allowed us to outline a hypothesis on the biological function as well as prospective applications of such atypical angucyclinones.
Collapse
Affiliation(s)
- Andrey A Mikhaylov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10 Miklukho-Maklaya St., Moscow, 117997, Russia.
| | | | | |
Collapse
|
5
|
Nicolaou KC, Chen Q, Li R, Anami Y, Tsuchikama K. Total Synthesis of the Monomeric Unit of Lomaiviticin A. J Am Chem Soc 2020; 142:20201-20207. [DOI: 10.1021/jacs.0c10660] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- K. C. Nicolaou
- Department of Chemistry, BioScience Research Collaborative, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Qifeng Chen
- Department of Chemistry, BioScience Research Collaborative, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Ruofan Li
- Department of Chemistry, BioScience Research Collaborative, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Yasuaki Anami
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, 1881 East Road, Houston, Texas 77054, United States
| | - Kyoji Tsuchikama
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, 1881 East Road, Houston, Texas 77054, United States
| |
Collapse
|
6
|
Winter N, Trauner D. Synthesis of acremines A, B and F and studies on the bisacremines. Beilstein J Org Chem 2019; 15:2271-2276. [PMID: 31598179 PMCID: PMC6774081 DOI: 10.3762/bjoc.15.219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 08/12/2019] [Indexed: 12/03/2022] Open
Abstract
The acremines are a family of meroterpenoids isolated from fungi of the genus Acremonium. Here, we present the asymmetric total synthesis of acremine F which hinges on a modestly enantioselective dihydroxylation and a subsequent kinetic resolution via a highly selective asymmetric reduction. Chemoselective oxidation of acremine F gave access to acremines A and B. The dimerization of acremine F to bisacremine E was investigated but could not be achieved, shedding light on the formation of the acremine dimers in nature.
Collapse
Affiliation(s)
- Nils Winter
- Department of Chemistry, University of Munich, Butenandtstraße 5–13, 81377 Munich, Germany
| | - Dirk Trauner
- Department of Chemistry, University of Munich, Butenandtstraße 5–13, 81377 Munich, Germany
- Department of Chemistry, New York University, 100 Washington Square East, Room 712, New York, NY 10003, USA
| |
Collapse
|
7
|
Haghdoost MM, Golbaghi G, Guard J, Sielanczyk S, Patten SA, Castonguay A. Synthesis, characterization and biological evaluation of cationic organoruthenium(ii) fluorene complexes: influence of the nature of the counteranion. Dalton Trans 2019; 48:13396-13405. [PMID: 31432885 DOI: 10.1039/c9dt00143c] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this study, five ruthenium arene complexes with fluorene-bearing N,N-(1) and N,O-(2) donor Schiff base ligands were synthesized and fully characterized. Cationic ruthenium complexes 3[X], ([Ru(η6-C6H6)(Cl)(fluorene-N[double bond, length as m-dash]CH-pyridine)][X] (where X = BF4, PF6, BPh4), were obtained by reacting ligand 1 with [Ru(η6-C6H6)Cl2]2 in the presence of NH4X salts, whereas neutral complex 4, Ru(η6-C6H6)(Cl)(fluorene-N[double bond, length as m-dash]CH-naphtholate), was isolated by reacting ligand 2 with the same precursor. It was possible to obtain a cationic version of the latter, 5[BF4], by reacting 4 with AgBF4 in the presence of pyridine. All compounds were fully characterized by NMR and HR-ESI-MS whereas some of them were also analyzed by single crystal X-ray analysis. Their in vitro antiproliferative activity was also assessed in human breast cancer cell lines, notably MCF-7 and T47D. Complex 4 and its cationic counterpart 5[BF4] were found to be the most cytotoxic compounds of the series (IC50 = 6.2-16.2 μM) and displayed higher antiproliferative activities than cisplatin in both cell lines. It was found that 5[BF4] undergoes a ligand exchange reaction and readily converts to 4 in the presence of 0.1 M NaCl, explaining the similarity in their observed cytotoxicities. Whereas 3[BF4] and 3[PF6] were found inactive at the tested concentrations, 3[BPh4] displayed a considerable cytotoxicity (IC50 = 16.7-27.8 μM). Notably, 3[BPh4], 4 (and 5[BF4]) were active against T47D, a cisplatin resistant cell line. Interestingly, 4 (16.4 μM) was found to be less cytotoxic than 3[BPh4] and cisplatin (6.6 and 7.9 μM, respectively) in breast healthy cells (MCF-12A). However, in comparison to 4 and cisplatin (at 10 μM), a lower in vivo toxicity was observed for complex 3[BPh4] on the development of zebrafish (Danio rerio) embryos.
Collapse
Affiliation(s)
- Mohammad Mehdi Haghdoost
- INRS - Centre Armand-Frappier Santé Biotechnology, Université du Québec, 531 boul. des Prairies, Laval, Quebec H7V 1B7, Canada.
| | - Golara Golbaghi
- INRS - Centre Armand-Frappier Santé Biotechnology, Université du Québec, 531 boul. des Prairies, Laval, Quebec H7V 1B7, Canada.
| | - Juliette Guard
- INRS - Centre Armand-Frappier Santé Biotechnology, Université du Québec, 531 boul. des Prairies, Laval, Quebec H7V 1B7, Canada.
| | - Sarah Sielanczyk
- INRS - Centre Armand-Frappier Santé Biotechnology, Université du Québec, 531 boul. des Prairies, Laval, Quebec H7V 1B7, Canada.
| | - Shunmoogum A Patten
- INRS - Centre Armand-Frappier Santé Biotechnology, Université du Québec, 531 boul. des Prairies, Laval, Quebec H7V 1B7, Canada.
| | - Annie Castonguay
- INRS - Centre Armand-Frappier Santé Biotechnology, Université du Québec, 531 boul. des Prairies, Laval, Quebec H7V 1B7, Canada.
| |
Collapse
|
8
|
Chen R, Liu Y, Cui S. 1,4-Conjugate addition/esterification of ortho-quinone methides in a multicomponent reaction. Chem Commun (Camb) 2018; 54:11753-11756. [DOI: 10.1039/c8cc07328g] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel 1,4-conjugate addition/esterification of ortho-quinone methides in a multicomponent reaction has been developed for facilely accessing 3,3-diarylpropanamides.
Collapse
Affiliation(s)
- Renjie Chen
- Institute of Drug Discovery and Design, College of Pharmaceutical Sciences, Zhejiang University
- Hangzhou 310058
- P. R. China
| | - Yu Liu
- Sate Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University
- Hangzhou 310058
- China
| | - Sunliang Cui
- Institute of Drug Discovery and Design, College of Pharmaceutical Sciences, Zhejiang University
- Hangzhou 310058
- P. R. China
| |
Collapse
|
9
|
Abstract
(-)-Lomaiviticin A (4) is a complex C2-symmetric bacterial metabolite that contains two diazofluorene functional groups. The diazofluorene consists of naphthoquinone, cyclopentadiene, and diazo substituents fused through a σ- and π-bonding network. Additionally, (-)-lomaiviticin A (4) is a potent cytotoxin, with half-maximal inhibitory potency (IC50) values in the low nanomolar range against many cancer cell lines. Because of limitations in supply, its mechanism of action had remained a "black box" since its isolation in the early 2000s. In this Account, I describe how studies directed toward the total synthesis of (-)-lomaiviticin A (4) provided a platform to elucidate the emergent properties of this metabolite and thereby connect chemical reactivity with cellular phenotype. We first developed a convergent strategy to prepare the diazofluorene (9 + 10 → 13). We then adapted this chemistry to the synthesis of lomaiviticin aglycon (21/22) and the natural monomeric diazofluorene (-)-kinamycin F (3). The key step in the lomaiviticin aglycon (21/22) synthesis involved the stereoselective oxidative coupling of two monomeric diazofluorenes (2 × 18 → 20) to establish the cojoining carbon-carbon bond of the target. As the absolute stereochemistry of the aglycon and carbohydrate residues of (-)-lomaiviticin A (4) were unknown, we developed a semisynthetic route to the metabolite that proceeds in one step and 42% yield by diazo transfer to the more abundant isolate (-)-lomaiviticin C (6). This allowed us to complete the stereochemical assignment of (-)-lomaiviticin A (4) and provided a renewable source of material. Using this material, we established that the remarkable cytotoxic effects of (-)-lomaiviticin A (4) derive from the induction of highly toxic double-strand breaks (DSBs) in DNA. At the molecular level, 1,7-nucleophilic additions to each electrophilic diazofluorene trigger homolytic decomposition pathways that produce sp2 radicals at the carbon atoms of each diazo group. These radicals abstract hydrogen atoms from the deoxyribose of DNA, a process known to initiate strand cleavage. NMR spectroscopy and molecular mechanics simulations were used to elucidate the mode of DNA binding. These studies showed that both diazofluorenes of (-)-lomaiviticin A (4) penetrate into the duplex. This mode of non-covalent binding places each diazo carbon atom in close proximity to each DNA strand. Throughout these studies, isolates containing one diazofluorene, such as (-)-lomaiviticin C (6) and (-)-kinamycin C (2), were used as controls. Consistent with our mechanistic model, these compounds do not induce DSBs in DNA and are several orders of magnitude less potent. Reactivity studies suggest that (-)-lomaiviticin A (4) is more electrophilic than simple monomeric diazofluorenes. We attribute this to through-space delocalization of the developing negative charge in the transition state for 1,7-addition. Consistent with this mechanism of action, (-)-lomaiviticin A (4) displays selective low-picomolar potencies toward DNA DSB repair-deficient cell types. The emergent properties of (-)-lomaiviticin A (4) derive from the specific arrangement of diazo, naphthoquinone, cyclopentadiene, and ketone functional groups. These functional groups work together to yield, essentially, a masked vinyl radical that can be exposed under biological conditions. Furthermore, the rotational symmetry of the metabolite, deriving from dimerization, allows it to interact with the antiparallel symmetry of DNA and affect cleavage of the duplex.
Collapse
Affiliation(s)
- Seth B. Herzon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States. Department of Pharmacology, Yale School of Medicine, New Haven, Connecticut 06520, United States
| |
Collapse
|
10
|
Fu W, Zhang Z, Zhuang P, Shen J, Ye M. One-pot hydrothermal synthesis of magnetically recoverable palladium/reduced graphene oxide nanocomposites and its catalytic applications in cross-coupling reactions. J Colloid Interface Sci 2017; 497:83-92. [DOI: 10.1016/j.jcis.2017.02.063] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 02/24/2017] [Accepted: 02/26/2017] [Indexed: 10/20/2022]
|
11
|
Waldman AJ, Ng TL, Wang P, Balskus EP. Heteroatom-Heteroatom Bond Formation in Natural Product Biosynthesis. Chem Rev 2017; 117:5784-5863. [PMID: 28375000 PMCID: PMC5534343 DOI: 10.1021/acs.chemrev.6b00621] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Natural products that contain functional groups with heteroatom-heteroatom linkages (X-X, where X = N, O, S, and P) are a small yet intriguing group of metabolites. The reactivity and diversity of these structural motifs has captured the interest of synthetic and biological chemists alike. Functional groups containing X-X bonds are found in all major classes of natural products and often impart significant biological activity. This review presents our current understanding of the biosynthetic logic and enzymatic chemistry involved in the construction of X-X bond containing functional groups within natural products. Elucidating and characterizing biosynthetic pathways that generate X-X bonds could both provide tools for biocatalysis and synthetic biology, as well as guide efforts to uncover new natural products containing these structural features.
Collapse
Affiliation(s)
- Abraham J. Waldman
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Tai L. Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Peng Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Emily P. Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| |
Collapse
|
12
|
Shi Y, Gao S. Recent advances of synthesis of fluorenone and fluorene containing natural products. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.02.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
13
|
Cai S, Xiao Z, Ou J, Shi Y, Gao S. A photo-induced C–C bond formation methodology to construct tetrahydrofluorenones and their related structures. Org Chem Front 2016. [DOI: 10.1039/c5qo00392j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A metal-free, photo-induced C–C bond formation methodology was developed to construct tetrahydrofluorenones and their related structures.
Collapse
Affiliation(s)
- Shujun Cai
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
| | - Zheming Xiao
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
| | - Jinjie Ou
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
| | - Yingbo Shi
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
| | - Shuanhu Gao
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
| |
Collapse
|
14
|
|
15
|
Hsiao CC, Liao HH, Rueping M. Enantio- and Diastereoselective Access to Distant Stereocenters Embedded within Tetrahydroxanthenes: Utilizingortho-Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalysis. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201406587] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
16
|
Hsiao CC, Liao HH, Rueping M. Enantio- and Diastereoselective Access to Distant Stereocenters Embedded within Tetrahydroxanthenes: Utilizingortho-Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalysis. Angew Chem Int Ed Engl 2014; 53:13258-63. [DOI: 10.1002/anie.201406587] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Indexed: 11/10/2022]
|
17
|
Cai S, Xiao Z, Shi Y, Gao S. The Photo-Nazarov Reaction: Scope and Application. Chemistry 2014; 20:8677-81. [DOI: 10.1002/chem.201402993] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Indexed: 11/09/2022]
|
18
|
Moebius DC, Rendina VL, Kingsbury JS. Catalysis of diazoalkane-carbonyl homologation. How new developments in hydrazone oxidation enable the carbon insertion strategy for synthesis. Top Curr Chem (Cham) 2014; 346:111-62. [PMID: 24770564 DOI: 10.1007/128_2013_521] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Diazo compounds continue both to challenge and to fascinate practitioners of chemical synthesis. The most strategically powerful and unique type of reactivity observed with these reagents is a formal insertion of the donor-acceptor carbon into C-C or C-H bonds alpha to carbonyl groups. Although the reaction does not involve discrete carbon-metal bonds, it can be catalyzed by metal-based Lewis acids. This chapter investigates both classical and modern developments in diazoalkyl carbon insertion with a special emphasis on nonstabilized nucleophiles.
Collapse
Affiliation(s)
- David C Moebius
- Onyx Pharmaceuticals, Inc., 249 E. Grand Avenue, South San Francisco, CA, 94080, USA
| | | | | |
Collapse
|
19
|
Abbott GL, Wu X, Zhao Z, Guo L, Birman VB, Hasinoff BB, Dmitrienko GI. Prekinamycin and an isosteric-isoelectronic analogue exhibit comparable cytotoxicity towards K562 human leukemia cells. MEDCHEMCOMM 2014. [DOI: 10.1039/c4md00197d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The diazo functionality of the kinamycins may not be an absolute requirement for bioactivity.
Collapse
Affiliation(s)
- Glenn L. Abbott
- Department of Chemistry
- University of Waterloo
- Waterloo, Canada
| | - Xing Wu
- Faculty of Pharmacy
- Apotex Centre
- University of Manitoba
- Winnipeg, Canada
| | - Zhufeng Zhao
- Department of Chemistry
- Washington University
- St Louis, USA
| | - Lei Guo
- Department of Chemistry
- Washington University
- St Louis, USA
| | | | - Brian B. Hasinoff
- Faculty of Pharmacy
- Apotex Centre
- University of Manitoba
- Winnipeg, Canada
| | | |
Collapse
|
20
|
Ouzouni MD, Fokas D. Synthetic Studies of Kinamycin Antibiotics: Stereoselective Synthesis of the Highly Oxygenated D-Ring and Construction of the ABD-Ring System of Kinamycins. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300858] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
21
|
Woo CM, Gholap SL, Herzon SB. Insights into lomaiviticin biosynthesis. Isolation and structure elucidation of (-)-homoseongomycin. JOURNAL OF NATURAL PRODUCTS 2013; 76:1238-1241. [PMID: 23803003 DOI: 10.1021/np400355h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The dimeric diazofluorenes known as the lomaiviticins are produced by the marine bacterium Salinispora pacifica DPJ-0019. Investigation of the fermentation broth of DPJ-0019 has yielded the first monomeric benzo[b]fluorene isolated from this species, (-)-homoseongomycin (13). (-)-Homoseongomycin (13) is related to the known natural product seongomycin (10), which is co-produced with the monomeric diazofluorenes known as the kinamycins. We describe the synthesis of the isotopically labeled derivative homoseongomycin-d5 (14), via the intermediacy of the diazofluorene "prelomaiviticin-d5" (12). Our studies establish that (-)-homoseongomycin (13) may be derived from prelomaiviticin (11) and suggest that 13 and 10 are shunt or detoxification metabolites in lomaiviticin and kinamycin biosynthesis, respectively.
Collapse
Affiliation(s)
- Christina M Woo
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | | | | |
Collapse
|
22
|
Mitcheltree MJ, Konst ZA, Herzon SB. A practical method for regiocontrolled one-carbon ring contraction. Tetrahedron Lett 2013; 69:5634-5639. [PMID: 34012174 DOI: 10.1016/j.tet.2013.04.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A practical and efficient method for the perfluorobutanesulfonyl azide-mediated one-carbon ring contraction of cyclic enoxysilanes is described. High-yielding procedures for the elaboration of the resulting N-acyl sulfonamide products are reported.
Collapse
Affiliation(s)
| | - Zef A Konst
- Department of Chemistry, Yale University, New Haven, CT 06511, United States
| | - Seth B Herzon
- Department of Chemistry, Yale University, New Haven, CT 06511, United States
| |
Collapse
|
23
|
Ischay MA, Takase MK, Bergman RG, Ellman JA. Unstabilized azomethine ylides for the stereoselective synthesis of substituted piperidines, tropanes, and azabicyclo[3.1.0] systems. J Am Chem Soc 2013; 135:2478-81. [PMID: 23398467 DOI: 10.1021/ja312311k] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Acid treatment of densely substituted 2-silyl-1,2-dihydropyridines provides a new and convenient entry to reactive azomethine ylides that can (1) be protonated and reduced with high stereoselectivity to give piperidines, (2) participate in [3 + 2] dipolar cycloaddition to give tropanes, and (3) undergo a Nazarov-like 6-π electrocyclization that upon reduction give 2-azabicyclo[3.1.0] systems.
Collapse
Affiliation(s)
- Michael A Ischay
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | | | | | | |
Collapse
|
24
|
Woo CM, Gholap SL, Lu L, Kaneko M, Li Z, Ravikumar PC, Herzon SB. Development of enantioselective synthetic routes to (-)-kinamycin F and (-)-lomaiviticin aglycon. J Am Chem Soc 2012; 134:17262-73. [PMID: 23030272 PMCID: PMC3505684 DOI: 10.1021/ja307497h] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The development of enantioselective synthetic routes to (-)-kinamycin F (9) and (-)-lomaiviticin aglycon (6) are described. The diazotetrahydrobenzo[b]fluorene (diazofluorene) functional group of the targets was prepared by fluoride-mediated coupling of a β-trimethylsilylmethyl-α,β-unsaturated ketone (38) with an oxidized naphthoquinone (19), palladium-catalyzed cyclization (39→37), and diazo transfer (37→53). The D-ring precursors 60 and 68 were prepared from m-cresol and 3-ethylphenol, respectively. Coupling of the β-trimethylsilylmethyl-α,β-unsaturated ketone 60 with the juglone derivative 61, cyclization, and diazo transfer provided the advanced diazofluorene 63, which was elaborated to (-)-kinamycin F (9) in three steps. The diazofluorene 87 was converted to the C(2)-symmetric lomaiviticin aglycon precursor 91 by enoxysilane formation and oxidative dimerization with manganese tris(hexafluoroacetylacetonate) (94, 26%). The stereochemical outcome in the coupling is attributed to the steric bias engendered by the mesityl acetal of 87 and contact ion pairing of the intermediates. The coupling product 91 was deprotected (tert-butylhydrogen peroxide, trifluoroacetic acid-dichloromethane) to form mixtures of the chain isomer of lomaiviticin aglycon 98 and the ring isomer 6. These mixtures converged on purification or standing to the ring isomer 6 (39-41% overall). The scope of the fluoride-mediated coupling process is delineated (nine products, average yield = 72%); a related enoxysilane quinonylation reaction is also described (10 products, average yield = 77%). We establish that dimeric diazofluorenes undergo hydrodediazotization 2-fold faster than related monomeric diazofluorenes. This enhanced reactivity may underlie the cytotoxic effects of (-)-lomaiviticin A (1). The simple diazofluorene 103 is a potent inhibitor of ovarian cancer stem cells (IC(50) = 500 nM).
Collapse
Affiliation(s)
- Christina M. Woo
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | | | - Liang Lu
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - Miho Kaneko
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - Zhenwu Li
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - P. C. Ravikumar
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - Seth B. Herzon
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| |
Collapse
|
25
|
Woo CM, Beizer NE, Janso JE, Herzon SB. Isolation of Lomaiviticins C–E, Transformation of Lomaiviticin C to Lomaiviticin A, Complete Structure Elucidation of Lomaiviticin A, and Structure–Activity Analyses. J Am Chem Soc 2012; 134:15285-8. [DOI: 10.1021/ja3074984] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christina M. Woo
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United
States
| | - Nina E. Beizer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United
States
| | - Jeffrey E. Janso
- Natural Products
− Worldwide
Medicinal Chemistry, Pfizer Worldwide Research and Development, 445 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Seth B. Herzon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United
States
| |
Collapse
|
26
|
Nicolaou KC, Hale CRH, Nilewski C, Ioannidou HA. Constructing molecular complexity and diversity: total synthesis of natural products of biological and medicinal importance. Chem Soc Rev 2012; 41:5185-238. [PMID: 22743704 PMCID: PMC3426871 DOI: 10.1039/c2cs35116a] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The advent of organic synthesis and the understanding of the molecule as they occurred in the nineteenth century and were refined in the twentieth century constitute two of the most profound scientific developments of all time. These discoveries set in motion a revolution that shaped the landscape of the molecular sciences and changed the world. Organic synthesis played a major role in this revolution through its ability to construct the molecules of the living world and others like them whose primary element is carbon. Although the early beginnings of organic synthesis came about serendipitously, organic chemists quickly recognized its potential and moved decisively to advance and exploit it in myriad ways for the benefit of mankind. Indeed, from the early days of the synthesis of urea and the construction of the first carbon-carbon bond, the art of organic synthesis improved to impressively high levels of sophistication. Through its practice, today chemists can synthesize organic molecules--natural and designed--of all types of structural motifs and for all intents and purposes. The endeavor of constructing natural products--the organic molecules of nature--is justly called both a creative art and an exact science. Often called simply total synthesis, the replication of nature's molecules in the laboratory reflects and symbolizes the state of the art of synthesis in general. In the last few decades a surge in total synthesis endeavors around the world led to a remarkable collection of achievements that covers a wide ranging landscape of molecular complexity and diversity. In this article, we present highlights of some of our contributions in the field of total synthesis of natural products of biological and medicinal importance. For perspective, we also provide a listing of selected examples of additional natural products synthesized in other laboratories around the world over the last few years.
Collapse
Affiliation(s)
- K C Nicolaou
- Department of Chemistry and Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | | | | | | |
Collapse
|
27
|
Guo F, Clift MD, Thomson RJ. Oxidative Coupling of Enolates, Enol Silanes and Enamines: Methods and Natural Product Synthesis. European J Org Chem 2012; 2012:4881-4896. [PMID: 23471479 DOI: 10.1002/ejoc.201200665] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The oxidative coupling of enolates, enol silanes, and enamines provides a direct method for the construction of useful 1,4-dicarbonyl synthons. Despite being first reported in 1935, with subsequent important advances beginning in the 1970's, the development of this powerful reaction into a reliable methodology was somewhat limited. In recent years, there have been a number of reports from several research groups demonstrating advances in several neglected areas of oxidative coupling. This microreview summarizes these new advances in methodology and provides an overview of recent natural product syntheses that showcase the power of these transformations.
Collapse
Affiliation(s)
- Fenghai Guo
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, USA
| | | | | |
Collapse
|
28
|
|
29
|
Rao MLN, Giri S. Pd-catalyzed threefold arylations of mono, di and tetra-bromoquinones using triarylbismuth reagents. RSC Adv 2012. [DOI: 10.1039/c2ra22058j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
|
30
|
Suzuki T. Synthetic Study of Kinamycins and Lomaiviticins. J SYN ORG CHEM JPN 2012. [DOI: 10.5059/yukigoseikyokaishi.70.1069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
31
|
Herzon SB, Woo CM. The diazofluorene antitumor antibiotics: Structural elucidation, biosynthetic, synthetic, and chemical biological studies. Nat Prod Rep 2012; 29:87-118. [DOI: 10.1039/c1np00052g] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
32
|
Mulcahy SP, Woo CM, Ding W, Ellestad GA, Herzon SB. Characterization of a reductively-activated elimination pathway relevant to the biological chemistry of the kinamycins and lomaiviticins. Chem Sci 2012. [DOI: 10.1039/c2sc00854h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
33
|
Kharel MK, Pahari P, Shepherd MD, Tibrewal N, Nybo SE, Shaaban KA, Rohr J. Angucyclines: Biosynthesis, mode-of-action, new natural products, and synthesis. Nat Prod Rep 2011; 29:264-325. [PMID: 22186970 DOI: 10.1039/c1np00068c] [Citation(s) in RCA: 250] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: 1997 to 2010. The angucycline group is the largest group of type II PKS-engineered natural products, rich in biological activities and chemical scaffolds. This stimulated synthetic creativity and biosynthetic inquisitiveness. The synthetic studies used five different strategies, involving Diels-Alder reactions, nucleophilic additions, electrophilic additions, transition-metal mediated cross-couplings and intramolecular cyclizations to generate the angucycline frames. Biosynthetic studies were particularly intriguing when unusual framework rearrangements by post-PKS tailoring oxidoreductases occurred, or when unusual glycosylation reactions were involved in decorating the benz[a]anthracene-derived cores. This review follows our previous reviews, which were published in 1992 and 1997, and covers new angucycline group antibiotics published between 1997 and 2010. However, in contrast to the previous reviews, the main focus of this article is on new synthetic approaches and biosynthetic investigations, most of which were published between 1997 and 2010, but go beyond, e.g. for some biosyntheses all the way back to the 1980s, to provide the necessary context of information.
Collapse
Affiliation(s)
- Madan K Kharel
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 S. Limestone Street, Lexington, Kentucky 40536-0596, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
Scully SS, Porco JA. Asymmetric Total Synthesis of the Epoxykinamycin FL-120 B′. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201104504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
35
|
Scully SS, Porco JA. Asymmetric total synthesis of the epoxykinamycin FL-120 B'. Angew Chem Int Ed Engl 2011; 50:9722-6. [PMID: 21953671 DOI: 10.1002/anie.201104504] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Stephen S Scully
- Department of Chemistry and Center for Chemical Methodology and Library Development, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | | |
Collapse
|
36
|
Kimura S, Kobayashi S, Kumamoto T, Akagi A, Sato N, Ishikawa T. Syntheses of Prekinamycin and a Tetracyclic Quinone from Common Synthetic Intermediates. Helv Chim Acta 2011. [DOI: 10.1002/hlca.201000296] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
37
|
Lee HG, Ahn JY, Lee AS, Shair MD. Enantioselective synthesis of the lomaiviticin aglycon full carbon skeleton reveals remarkable remote substituent effects during the dimerization event. Chemistry 2011; 16:13058-62. [PMID: 20976820 DOI: 10.1002/chem.201002157] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hong Geun Lee
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
| | | | | | | |
Collapse
|
38
|
Herzon SB, Lu L, Woo CM, Gholap SL. 11-Step enantioselective synthesis of (-)-lomaiviticin aglycon. J Am Chem Soc 2011; 133:7260-3. [PMID: 21280607 DOI: 10.1021/ja200034b] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lomaiviticins A and B are complex antitumor antibiotics that were isolated from a strain of Micromonospora. A confluence of several unusual structural features renders the lomaiviticins exceedingly challenging targets for chemical synthesis. We report an 11-step, enantioselective synthetic route to lomaiviticin aglycon. Our route proceeds by late-stage, stereoselective dimerization of two equivalent monomeric intermediates, a transformation that may share parallels with the natural products' biosyntheses. The route we describe is scalable and convergent, and it lays the foundation for determination of the mode of action of these natural products.
Collapse
Affiliation(s)
- Seth B Herzon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
| | | | | | | |
Collapse
|
39
|
|
40
|
Affiliation(s)
- Takuya KUMAMOTO
- Graduate School of Pharmaceutical Sciences, Chiba University
| |
Collapse
|