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Badart MP, Hawkins BC. Synthetic Strategies to Access Heteroatomic Spirocentres Embedded in Natural Products. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/a-1379-2312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
AbstractThe spirocyclic motif is abundant in natural products and provides an ideal three-dimensional template to interact with biological targets. With significant attention historically expended on the synthesis of flat-heterocyclic compound libraries, methods to access the less-explored three-dimensional medicinal-chemical space will continue to increase in demand. Herein, we highlight by reaction class the common strategies used to construct the spirocyclic centres embedded in a series of well-studied natural products.1 Introduction2 Cycloadditions3 Palladium-Catalysed Coupling Reactions4 Conjugate Additions5 Imines, Aminals, and Hemiaminal Ethers6 Mannich-Type Reactions7 Oxidative Dearomatisation8 Alkylation9 Organometallic Additions10 Conclusions
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2
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Hu J, Bian M, Ding H. Recent application of oxa-Michael reaction in complex natural product synthesis. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.11.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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3
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Affiliation(s)
- Bing Xu
- Beijing
National Laboratory for Molecular Sciences, CAS Key Laboratory of
Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Guang Li
- Beijing
National Laboratory for Molecular Sciences, CAS Key Laboratory of
Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jing Li
- Beijing
National Laboratory for Molecular Sciences, CAS Key Laboratory of
Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yian Shi
- Beijing
National Laboratory for Molecular Sciences, CAS Key Laboratory of
Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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Mailyan AK, Eickhoff JA, Minakova AS, Gu Z, Lu P, Zakarian A. Cutting-Edge and Time-Honored Strategies for Stereoselective Construction of C–N Bonds in Total Synthesis. Chem Rev 2016; 116:4441-557. [DOI: 10.1021/acs.chemrev.5b00712] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Artur K. Mailyan
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - John A. Eickhoff
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Anastasiia S. Minakova
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Zhenhua Gu
- Department
of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Ping Lu
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Armen Zakarian
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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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.
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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
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Uchiro H, Kato R, Sakuma Y, Takagi Y, Arai Y, Hasegawa D. Synthetic studies of GKK1032s: the asymmetric synthesis of the decahydrofluorene skeleton via a novel cyclization of silyl enol ether and sequential retro Diels–Alder and intramolecular Diels–Alder reactions. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.09.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Sun Y, Gan J, Fan R. Facile Construction of Oxa-Aza Spirobicycles via a Tandem Carbon-Hydrogen Bond Oxidation. Adv Synth Catal 2011. [DOI: 10.1002/adsc.201100196] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Furey A, O'Doherty S, O'Callaghan K, Lehane M, James KJ. Azaspiracid poisoning (AZP) toxins in shellfish: Toxicological and health considerations. Toxicon 2010; 56:173-90. [DOI: 10.1016/j.toxicon.2009.09.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Accepted: 09/18/2009] [Indexed: 11/29/2022]
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Synthesis of oxa-aza spirobicycles by intramolecular hydrogen atom transfer promoted by N-radicals in carbohydrate systems. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.05.049] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Frederick MO, Janda KD, Nicolaou KC, Dickerson TJ. Monoclonal antibodies with orthogonal azaspiracid epitopes. Chembiochem 2009; 10:1625-9. [PMID: 19492388 PMCID: PMC2750835 DOI: 10.1002/cbic.200900201] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Indexed: 12/29/2022]
Abstract
Azaspiracid antibodies: Immunization of azaspiracid immunoconjugates has elicited monoclonal antibodies with distinct epitopes on the marine toxin; this will open the way toward azaspiracid diagnostics and the detection of contaminated shellfish before they can enter the food supply.
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Affiliation(s)
- Michael O. Frederick
- Department of Chemistry and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (USA) and Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Kim D. Janda
- Departments of Chemistry and Immunology, The Skaggs Institute of Chemical Biology and Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (USA)
| | - K. C. Nicolaou
- Department of Chemistry and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (USA) and Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (USA)
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Abstract
The last one hundred years have witnessed a dramatic increase in the power and reach of total synthesis. The pantheon of accomplishments in the field includes the total synthesis of molecules of unimaginable beauty and diversity such as the four discussed in this article: endiandric acids (1982), calicheamicin gamma(1)(I) (1992), Taxol (1994), and brevetoxin B (1995). Chosen from the collection of the molecules synthesized in the author's laboratories, these structures are but a small fraction of the myriad constructed in laboratories around the world over the last century. Their stories, and the background on which they were based, should serve to trace the evolution of the art of chemical synthesis to its present sharp condition, an emergence that occurred as a result of new theories and mechanistic insights, new reactions, new reagents and catalysts, and new synthetic technologies and strategies. Indeed, the advent of chemical synthesis as a whole must be considered as one of the most influential developments of the twentieth century in terms of its impact on society.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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Evans DA, Kvaernø L, Dunn TB, Beauchemin A, Raymer B, Mulder JA, Olhava EJ, Juhl M, Kagechika K, Favor DA. Total synthesis of (+)-azaspiracid-1. An exhibition of the intricacies of complex molecule synthesis. J Am Chem Soc 2008; 130:16295-309. [PMID: 19006391 PMCID: PMC3408805 DOI: 10.1021/ja804659n] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accomplished by aldol and sulfone anion methodologies. All ketalization events to form the nonacyclic target were accomplished under equilibrating conditions utilizing the imbedded configurations of the molecule to adopt one favored conformation. A final fragment coupling of the anomeric EFGHI-sulfone anion to the ABCD-aldehyde completed the convergent synthesis of (+)-azaspiracid-1.
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Affiliation(s)
- David A Evans
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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Affiliation(s)
- Marie‐Eve Sinibaldi
- Laboratoire de Synthèse et Etude de Systèmes à Intérêt Biologique (SEESIB), UMR 6504, Université Blaise Pascal, 63177 Aubière Cedex, France, Fax: +33‐4‐73407717
| | - Isabelle Canet
- Laboratoire de Synthèse et Etude de Systèmes à Intérêt Biologique (SEESIB), UMR 6504, Université Blaise Pascal, 63177 Aubière Cedex, France, Fax: +33‐4‐73407717
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Nicolaou KC, Lister T, Denton RM, Gelin CF. Total synthesis of atrochamins F, H, I, and J through cascade reactions. Tetrahedron 2008; 64:4736-4757. [PMID: 19461992 DOI: 10.1016/j.tet.2008.02.108] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A concise and efficient cascade-based total synthesis of artochamins F, H, I, and J is described. The potential biogenetic connection between artochamin F, or a derivative thereof, and artochamins H, I, and J, through an unusual formal [2+2] cycloaddition process, was shown to be feasible. An alternative mechanism for this transformation is also proposed.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla 92037, U.S.A
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Francisco CG, Freire R, Herrera AJ, Pérez-Martín I, Suárez E. Intramolecular 1,5- versus 1,6-hydrogen abstraction reaction promoted by alkoxyl radicals in pyranose and furanose models. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.06.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yadav J, Joyasawal S, Dutta S, Kunwar A. Stereoselective synthesis of the ABCD ring framework of azaspiracids. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.05.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Evans D, Kværnø L, Mulder J, Raymer B, Dunn T, Beauchemin A, Olhava E, Juhl M, Kagechika K. Total Synthesis of (+)-Azaspiracid-1. Part I: Synthesis of the Fully Elaborated ABCD Aldehyde. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200701515] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Evans DA, Kvaernø L, Mulder JA, Raymer B, Dunn TB, Beauchemin A, Olhava EJ, Juhl M, Kagechika K. Total Synthesis of (+)-Azaspiracid-1. Part I: Synthesis of the Fully Elaborated ABCD Aldehyde. Angew Chem Int Ed Engl 2007; 46:4693-7. [PMID: 17546577 DOI: 10.1002/anie.200701515] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- David A Evans
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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Nakashima K, Kikuchi N, Shirayama D, Miki T, Ando K, Sono M, Suzuki S, Kawase M, Kondoh M, Sato M, Tori M. Total Synthesis and Cytotoxicity of (+)- and (−)-Goniodiol and 6-epi-Goniodiol. Construction of α,β-Unsaturated Lactones by Ring-Closing Metathesis. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.387] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Nicolaou KC, Snyder SA. Chasing molecules that were never there: misassigned natural products and the role of chemical synthesis in modern structure elucidation. Angew Chem Int Ed Engl 2007; 44:1012-1044. [PMID: 15688428 DOI: 10.1002/anie.200460864] [Citation(s) in RCA: 479] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Over the course of the past half century, the structural elucidation of unknown natural products has undergone a tremendous revolution. Before World War II, a chemist would have relied almost exclusively on the art of chemical synthesis, primarily in the form of degradation and derivatization reactions, to develop and test structural hypotheses in a process that often took years to complete when grams of material were available. Today, a battery of advanced spectroscopic methods, such as multidimensional NMR spectroscopy and high-resolution mass spectrometry, not to mention X-ray crystallography, exist for the expeditious assignment of structures to highly complex molecules isolated from nature in milligram or sub-milligram quantities. In fact, it could be argued that the characterization of natural products has become a routine task, one which no longer even requires a reaction flask! This Review makes the case that imaginative detective work and chemical synthesis still have important roles to play in the process of solving nature's most intriguing molecular puzzles.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA, Fax: (+1) 858-784-2469
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Scott A Snyder
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA, Fax: (+1) 858-784-2469
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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Zhou XT, Lu L, Furkert DP, Wells CE, Carter RG. Synthesis of the southern FGHI ring system of azaspiracid-1 and investigation into the controlling elements of C28- and C36-ketalization. Angew Chem Int Ed Engl 2006; 45:7622-6. [PMID: 17044107 PMCID: PMC2414259 DOI: 10.1002/anie.200603353] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xiao-Ti Zhou
- Department of Chemistry Oregon State University Corvallis, OR 97331 USA Fax: (+ 1) 541−737−9496 E-mail:
| | - Liang Lu
- Department of Chemistry Oregon State University Corvallis, OR 97331 USA Fax: (+ 1) 541−737−9496 E-mail:
| | - Daniel P. Furkert
- Department of Chemistry Oregon State University Corvallis, OR 97331 USA Fax: (+ 1) 541−737−9496 E-mail:
| | - Charles E. Wells
- Department of Chemistry Oregon State University Corvallis, OR 97331 USA Fax: (+ 1) 541−737−9496 E-mail:
| | - Rich G. Carter
- Department of Chemistry Oregon State University Corvallis, OR 97331 USA Fax: (+ 1) 541−737−9496 E-mail:
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Zhou XT, Lu L, Furkert DP, Wells CE, Carter RG. Synthesis of the Southern FGHI Ring System of Azaspiracid-1 and Investigation into the Controlling Elements of C28- and C36-Ketalization. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200603353] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Nicolaou KC, Frederick MO, Loizidou EZ, Petrovic G, Cole KP, Koftis TV, Yamada YMA. Second-Generation Total Synthesis of Azaspiracids-1, -2, and -3. Chem Asian J 2006; 1:245-63. [PMID: 17441061 DOI: 10.1002/asia.200600059] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The naturally occurring but scarce marine neurotoxins azaspiracids-1, -2, and -3 have been synthesized from five key building blocks by a convergent strategy that involved dithiane and Stille coupling reactions. The ABCD fragments were constructed through a cascade reaction involving deprotection/self-assembly of the precursors, while the FGHI fragment was forged by a neodymium triflate-induced cyclization. The final ring closure (ring G) was achieved, after the union of all fragments, through an iodoetherification reaction followed by reductive removal of the facilitating iodine residue. These improved, second-generation routes confirm the absolute structures and render all three azaspiracids readily available for biological studies.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Vinh-Thang H, Huang Q, Ungureanu A, Eić M, Trong-On D, Kaliaguine S. Structural and diffusion characterizations of steam-stable mesostructured zeolitic UL-ZSM-5 materials. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:4777-86. [PMID: 16649795 DOI: 10.1021/la0524465] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A series of mesoporous UL-ZSM-5 materials (Si/Al = 50) with different micro- and mesoporosity as well as crystallinity was prepared following the procedure proposed in one of our recent studies (Trong-On, D.; Kaliaguine, S. Angew. Chem. Int. Ed. 2001, 40, 3248-3251. Trong-On, D.; Kaliaguine, S. U.S. Patent 6,669,924, B1, 2003). These materials have zeolitic structure in the form of nanoparticles intergrown in the walls of the amorphous wormhole-like aluminosilicate mesopores of Al-Meso-50, which was used as a precursor in the synthesis. The structure, crystallinity, and textural properties of the synthesized materials, as well as a reference ZSM-5 zeolite sample, were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM)/scanning electron microscoy (SEM) analyses, Fourier transform infrared spectroscopy (FTIR), 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR), and nitrogen adsorption/desorption techniques. The acid properties were examined by FTIR of adsorbed pyridine. UL-ZSM-5 materials were shown to be highly hydrothermally stable. The diffusion of two C7 hydrocarbons, i.e., n-heptane and toluene, in four UL-ZSM-5 materials with different microporosities, related acidities, and crystallinities were investigated using the zero-length column (ZLC) method. Furthermore, the wormhole-like mesostructured aluminosilicate precursor (Al-Meso-50) and a reference MFI zeolite sample were also investigated using the same technique. A theoretical model considering a combination of mesopore diffusion (with surface slip in the main channels) with an activated, mainly surface diffusion mechanism in the intrawall biporous structure, was proposed and employed to interpret the experimental ZLC results. A classical Knudsen type of diffusion was replaced by an activated surface slip type of diffusion mechanism in the mesopores. The transport of n-heptane in UL-ZSM-5 materials was found to be mainly controlled by mesopore diffusion in the main-channel structure, while that of toluene was dominated by the intrawall diffusion process. Diffusion activation energies of n-heptane are about 2 times higher in comparison to toluene, which has a larger kinetic diameter. The main mesopore channel structure seems to appreciably contribute to the overall mass transport. Furthermore, the effect of hydrothermal treatment (20% steam at 800 degrees C for 24 h) on the diffusion of these two sorbates on UL-ZSM-5 materials was also evaluated.
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Affiliation(s)
- Hoang Vinh-Thang
- Department of Chemical Engineering, Université Laval, Ste-Foy, Québec, Canada, G1K 7P4
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Zhou XT, Carter RG. Synthesis of the C1–C26 Northern Portion of Azaspiracid-1: Kinetic versus Thermodynamic Control of the Formation of the Bis-spiroketal. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503733] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zhou XT, Carter RG. Synthesis of the C1-C26 northern portion of azaspiracid-1: kinetic versus thermodynamic control of the formation of the bis-spiroketal. Angew Chem Int Ed Engl 2006; 45:1787-90. [PMID: 16470899 PMCID: PMC2414258 DOI: 10.1002/anie.200503733] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Xiao-Ti Zhou
- Department of Chemistry, Oregon State University, Corvallis, 97331, USA
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Nicolaou KC, Pihko PM, Bernal F, Frederick MO, Qian W, Uesaka N, Diedrichs N, Hinrichs J, Koftis TV, Loizidou E, Petrovic G, Rodriquez M, Sarlah D, Zou N. Total Synthesis and Structural Elucidation of Azaspiracid-1. Construction of Key Building Blocks for Originally Proposed Structure. J Am Chem Soc 2006; 128:2244-57. [PMID: 16478178 DOI: 10.1021/ja0547477] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Syntheses of the three key building blocks (65, 98, and 100) required for the total synthesis of the proposed structure of azaspiracid-1 (1a) are described. Key steps include a TMSOTf-induced ring-closing cascade to form the ABC rings of tetracycle 65, a neodymium-catalyzed internal aminal formation for the construction of intermediate 98, and a Nozaki-Hiyama-Kishi coupling to assemble the required carbon chain of fragment 100. The synthesized fragments, obtained stereoselectively in both their enantiomeric forms, were expected to allow for the construction of all four stereoisomers proposed as possible structures of azaspiracid-1 (1a-d), thus allowing the determination of both the relative and absolute stereochemistry of the natural product.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Larsen US, Martiny L, Begtrup M. Synthesis of 4-substituted tetrahydropyridines by cross-coupling of enol phosphates. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2005.03.203] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hoang VT, Huang Q, Eić M, Do TO, Kaliaguine S. Structure and diffusion characterization of SBA-15 materials. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2051-7. [PMID: 15723510 DOI: 10.1021/la048349d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In situ formation of the micro- and mesoporous structures of SBA-15 materials was investigated. It was found that the structure is significantly different from that for cylindrical or hexagonal pores, which suggests that the SBA-15 is more complex than an array of hexagonally ordered channels. Nitrogen adsorption isotherms at 77 K provided evidence that large (primary) mesopores are accompanied by a certain amount of significantly smaller pores with a broad distribution in the micropore/small-mesopore range within the mesoporous walls of main channels. It was found that the microporosity can be controlled by the time of heating as well as the synthesis temperature. The diffusion properties of n-heptane as a probe molecule in four selected SBA-15 samples with different micropore volumes were studied by the standard zero length column technique and related to their structural characteristics. The results have shown that the diffusion process involving n-heptane at a low concentration level takes place inside the walls of main mesoporous channels and depends on the relative content of micropores. In the samples that have a relatively high content of micropores, n-heptane diffusivities are relatively low, their activation energies are high, and the process is similar to diffusion in typical microporous adsorbents, like zeolites. As the micropore content is decreased, diffusion becomes more and more controlled by secondary mesopores of the intrawall pore structure, rendering diffusion faster and activation energies lower.
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Affiliation(s)
- Vinh-Thang Hoang
- Department of Chemical Engineering, Laval University, Ste-Foy, Québec, Canada G1K 7P4
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34
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Nicolaou KC, Snyder SA. Die Jagd auf Moleküle, die nie existiert haben: Falsch zugeordnete Naturstoffstrukturen und die Rolle der chemischen Synthese in der modernen Strukturaufklärung. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200460864] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- K. C. Nicolaou
- Department of Chemistry und The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA, Fax: (+1) 858‐784‐2469
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Scott A. Snyder
- Department of Chemistry und The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA, Fax: (+1) 858‐784‐2469
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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James KJ, Fidalgo Sáez MJ, Furey A, Lehane M. Azaspiracid poisoning, the food-borne illness associated with shellfish consumption. ACTA ACUST UNITED AC 2004; 21:879-92. [PMID: 15666982 DOI: 10.1080/02652030400002105] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Azaspiracid poisoning (AZP) is a recently discovered toxic syndrome that was identified following severe gastrointestinal illness from the consumption of contaminated mussels (Mytilus edulis). The implicated toxins, azaspiracids, are polyethers with unprecedented structural features. Studies toward total toxin synthesis revealed that the initial published structures were incorrect and they have now been revised. These toxins accumulate in bivalve molluscs that feed on toxic microalgae of the genus Protoperidinium, previously considered to be toxicologically benign. Although first identified in shellfish from Ireland, azaspiracid contamination of several types of bivalve shellfish species has now been confirmed throughout the western coastline of Europe. Toxicological studies have indicated that azaspiracids can induce widespread organ damage in mice and that they are probably more dangerous than previously known classes of shellfish toxins. The exclusive reliance on live animal bioassays to monitor azaspiracids in shellfish failed to prevent human intoxications. This was a consequence of poor sensitivity of the assay and the fact that azaspiracids are not exclusively found in the shellfish digestive glands used for toxin testing. The strict regulatory control of azaspiracids in shellfish now requires frequent testing of shellfish using highly specific and sensitive methods involving liquid chromatography-mass spectrometry.
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Affiliation(s)
- K J James
- Proteobio, Mass Spectrometry Centre for Proteomics and Biotoxin Research, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland.
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Nishiyama S, Ishikawa Y. Synthesis of the ABCD Ring System of Azaspiracid, a Marine Poison from Mytilus edulis. HETEROCYCLES 2004. [DOI: 10.3987/com-03-10000] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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37
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Synthesis of the BCD ring system of azaspiracid: construction of the trispiro ring structure by the thioether approach. Tetrahedron Lett 2004. [DOI: 10.1016/j.tetlet.2003.10.161] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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39
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Díaz Sierra M, Furey A, Hamilton B, Lehane M, James KJ. Elucidation of the fragmentation pathways of azaspiracids, using electrospray ionisation, hydrogen/deuterium exchange, and multiple-stage mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2003; 38:1178-1186. [PMID: 14648825 DOI: 10.1002/jms.526] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Collision-induced dissociation (CID) mass spectra were generated for azaspiracids using electrospray ionisation (ESI), and hydrogen/deuterium (H/D) exchange was used to ascertain the number and type of replaceable hydrogens in the three predominant azaspiracid toxins. H/D exchange was conveniently achieved using deuterated solvents for liquid chromatography (LC). Using ion-trap mass spectrometry, multiple-stage CID experiments (MS(n)) on the protonated and fully exchanged ions were performed to decipher characteristic fragmentation pathways. The precursor and product ions from azaspiracids lost up to five water molecules from different regions during MS(n) experiments and it was possible to distinguish between the water losses from different molecular regions. These studies confirmed that the first water-loss ion in the spectra of azaspiracids resulted from dehydration at the vicinal diol at C20-C21. Five MS dissociation pathways were identified that resulted from fragmentation of the carbon skeleton of azaspiracids producing nitrogen-containing ions. Two pathways, involving cleavage of the E-ring and C27-C28, gave ions that were found in all azaspiracids. Three pathways, A-ring, C-ring and C19-C20 cleavages, were useful for distinguishing between azaspiracid analogues. The same product ions from backbone fragmentation were also observed using hybrid quadrupole time-of-flight mass spectrometry (QqTOFMS). The fragmentation of the A-ring was the most facile and was exploited in the development of LC/MS(n) methods for the analysis of azaspiracids.
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Affiliation(s)
- Mónica Díaz Sierra
- PROTEOBIO, Mass Spectrometry Centre for Proteomics and Biotoxin Research, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland
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Carter RG, Bourland T, Zhou XT, Gronemeyer MA. Controlling influences in bisspiroketal formation: synthesis of the ABC ring system of azaspiracid. Tetrahedron 2003. [DOI: 10.1016/j.tet.2003.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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41
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Meng X, Li D, Yang X, Yu Y, Wu S, Han Y, Yang Q, Jiang D, Xiao FS. Synthesis, Characterization, and Catalytic Activity of Mesostructured Titanosilicates Assembled from Polymer Surfactants with Preformed Titanosilicate Precursors in Strongly Acidic Media. J Phys Chem B 2003. [DOI: 10.1021/jp027405l] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiangju Meng
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Defeng Li
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Xiaoyu Yang
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Yi Yu
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Shuo Wu
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Yu Han
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Qing Yang
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Dazhen Jiang
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
| | - Feng-Shou Xiao
- State Key Laboratory of Inorganic Synthesis and Preparative and Chemistry & Department of Chemistry, Jilin University, Changchun 130023, P. R. China
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Lin HP, Mou CY. Structural and morphological control of cationic surfactant-templated mesoporous silica. Acc Chem Res 2002; 35:927-35. [PMID: 12437317 DOI: 10.1021/ar000074f] [Citation(s) in RCA: 359] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Micelle-templated mesoporous silica materials are rapidly becoming important in many fields of chemistry for hosting reactants or catalysts in confined space. Fine control of the pore size, wall structure, surface functionalization, defects, and morphology is needed for fine-tuning the pores as nanoreactors. We review the physical chemistry of solution silicate species and surfactants in the synthesis of mesoporous silicas. Controls in surfactant packing and liquid crystalline phase transformation can lead to various tailored synthesis strategies. Postsynthesis treatments further make more stable mesoporous materials.
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Affiliation(s)
- Hong-Ping Lin
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan 115
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45
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Freire R, Martı́n A, Pérez-Martı́n I, Suárez E. Synthesis of oxa-aza spirobicycles by intramolecular hydrogen abstraction promoted by N -radicals in carbohydrate systems. Tetrahedron Lett 2002. [DOI: 10.1016/s0040-4039(02)00983-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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46
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Carter RG, Bourland TC, Graves DE. Synthesis of the ABC ring system of azaspiracid. 1. Effect of D ring truncation on bis-spirocyclization. Org Lett 2002; 4:2177-9. [PMID: 12074661 PMCID: PMC2424237 DOI: 10.1021/ol026033w] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] Synthesis of a spirocyclization precursor with a truncated D ring has been accomplished. Subsequent bis-spirocyclization induced the formation of equal amounts of the natural transoidal 10R,13R bis-spirocycle and its cisoidal 10R,13S epimer under an apparent thermodynamically controlled process.
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Affiliation(s)
- Rich G Carter
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, USA.
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Xiao FS, Han Y, Yu Y, Meng X, Yang M, Wu S. Hydrothermally stable ordered mesoporous titanosilicates with highly active catalytic sites. J Am Chem Soc 2002; 124:888-9. [PMID: 11829580 DOI: 10.1021/ja0170044] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mesoporous titanosilicates (MTS-9) are successfully prepared in strong acidic media by a two-step synthesis. MTS-9 has an ordered hexagonal structure and exhibits superior hydrothermal stability and high catalytic activity for the oxidation of the small molecules of phenol and styrene and also of the bulky molecule of trimethylphenol.
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Affiliation(s)
- Feng-Shou Xiao
- Department of Chemistry, Jilin University, Changchun 130023, China
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48
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Pauly TR, Petkov V, Liu Y, Billinge SJL, Pinnavaia TJ. Role of framework sodium versus local framework structure in determining the hydrothermal stability of MCM-41 mesostructures. J Am Chem Soc 2002; 124:97-103. [PMID: 11772066 DOI: 10.1021/ja0118183] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two mesostructured MCM-41 silicas that differ dramatically in hydrothermal stability have been examined by (29)Si MAS NMR spectroscopy and pair distribution function (PDF) analysis of synchrotron X-ray scattering data. The less stable mesostructure assembled from sodium silicate and the substantially more stable derivative made from fumed silica possess equivalent local framework wall structures, as judged by NMR and PDF methods. Approximately 80% of the SiO(4) tetrahedra are fully cross-linked as Q(4) (Si(OSi)(4)) units in both calcined samples. Additionally, the structural correlation distances for the two materials are nearly identical, having values of 1.62(1), approximately 2.60, and 3.09(1) A for the Si-O, O-O, and nearest neighbor Si-Si distances in the framework. Sodium ions in the framework play a crucial role in limiting the hydrothermal stability of the mesostructure. Residual sodium ( approximately 0.05-0.10% Na(2)O) is retained in the MCM-41 made from sodium silicate, even after two ion exchange reactions with ammonium ions in more than 300 - fold excess. The entrapped framework sodium ions catalyze the collapse of the mesopores upon exposure to 20% steam at 800 degrees C for 5 h. The sodium - free mesostructure assembled from fumed silica retains an open framework under the same hydrothermal conditions. The stability of the fumed silica derivative, however, is greatly compromised when doped with as little as 0.10% Na(2)O, thus confirming the deleterious effect of sodium on hydrothermal stability.
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Affiliation(s)
- Thomas R Pauly
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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50
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Forsyth CJ, Hao J, Aiguade J. Synthesis of the (+)‐C26–C40 Domain of the Azaspiracids by a Novel Double Intramolecular Hetero‐Michael Addition Strategy. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20011001)113:19<3775::aid-ange3775>3.0.co;2-#] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Craig J. Forsyth
- Department of Chemistry Institute of Technology University of Minnesota Minneapolis, MN 55455, USA, Fax: (+1) 612‐626‐7541
| | - Junliang Hao
- Department of Chemistry Institute of Technology University of Minnesota Minneapolis, MN 55455, USA, Fax: (+1) 612‐626‐7541
| | - Josep Aiguade
- Department of Chemistry Institute of Technology University of Minnesota Minneapolis, MN 55455, USA, Fax: (+1) 612‐626‐7541
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