51
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Kato H, Nakamura Y, Finefield JM, Umaoka H, Nakahara T, Williams RM, Tsukamoto S. Corrigendum to “Study on the biosynthesis of the notoamides: pinacol-type rearrangement of the isoprenyl unit in deoxybrevianamide E and 6-hydroxydeoxybrevianamide E” [Tetrahedron Lett. 52 (2011) 6923–6926]. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2013.11.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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52
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Guerra-Bubb JM, Bowers AA, Smith WB, Paranal R, Estiu G, Wiest O, Bradner JE, Williams RM. Synthesis and HDAC inhibitory activity of isosteric thiazoline-oxazole largazole analogs. Bioorg Med Chem Lett 2013; 23:6025-8. [PMID: 24035339 PMCID: PMC3859309 DOI: 10.1016/j.bmcl.2013.06.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 06/03/2013] [Indexed: 11/15/2022]
Abstract
The synthesis of an isosteric analog of the natural product and HDAC inhibitor largazole is described. The sulfur atom in the thizaole ring of the natural product has been replaced with an oxygen atom, constituting an oxazole ring. The biochemical activity and cytotoxicity of this species is described.
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53
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Jiménez-Somarribas A, Williams RM. Synthetic studies on lemonomycin: construction of the tetracyclic core. Tetrahedron 2013; 69:7505-7512. [PMID: 25083002 DOI: 10.1016/j.tet.2013.05.009] [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: 10/26/2022]
Abstract
A substrate-induced stereocontrol strategy was used to gain access to the tetracyclic core of (-)-lemonomycin. An advanced intermediate was prepared from a known substituted tyrosinol through a 16-step sequence, which involved a Pictet-Spengler reaction, a [3+2] dipolar cycloaddition and an enamide hydrogenation.
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54
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Bass PD, Gubler DA, Judd TC, Williams RM. Mitomycinoid alkaloids: mechanism of action, biosynthesis, total syntheses, and synthetic approaches. Chem Rev 2013; 113:6816-63. [PMID: 23654296 PMCID: PMC3864988 DOI: 10.1021/cr3001059] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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55
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Finefield JM, Williams RM. Correction to Synthesis of Notoamide J: A Potentially Pivotal Intermediate in the Biosynthesis of Several Prenylated Indole Alkaloids. J Org Chem 2013. [DOI: 10.1021/jo401209s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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56
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Tsukamoto S, Kato H, Greshock TJ, Hirota H, Ohta T, Williams RM. Correction to Isolation of Notoamide E, a Key Precursor in the Biosynthesis of Prenylated Indole Alkaloids in a Marine-Derived Fungus, Aspergillus sp. J Am Chem Soc 2013. [DOI: 10.1021/ja405894m] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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57
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Welch TR, Williams RM. Studies on the Biosynthesis of Chetomin: Enantiospecific Synthesis of a Putative, Late-Stage Biosynthetic Intermediate. Tetrahedron 2013; 69:770-773. [PMID: 24489414 DOI: 10.1016/j.tet.2012.10.075] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The enantiospecific synthesis of desthiochetomin, a putative biosynthetic intermediate of the epidithiodioxopiperazine natural product chetomin, is described. A diastereoselective N-alkylation was employed to form the key C3-N1' bond of the heterodimeric indoline core, followed by peptide coupling and dioxopiperazine cyclization with the requisite N-methyl amino acids. A related sarcosine-derived dioxopiperazine was prepared in the same manner. The first proposed biosynthesis of chetomin is also detailed in the text.
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58
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Sunderhaus JD, McAfoos TJ, Finefield JM, Kato H, Li S, Tsukamoto S, Sherman DH, Williams RM. Synthesis and bioconversions of notoamide T: a biosynthetic precursor to stephacidin A and notoamide B. Org Lett 2012; 15:22-5. [PMID: 23249380 DOI: 10.1021/ol302901p] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In an effort to further elucidate the biogenesis of the stephacidin and notoamide families of natural products, notoamide T has been identified as the likely precursor to stephacidin A. The total synthesis of notoamide T is described along with it is C-6-epimer, 6-epi-notoamide T. The chemical conversion of stephacidin A to notoamide T by reductive ring opening is described as well as the oxidative conversion of notoamide T to stephacidin A. Furthermore, [(13)C](2)-notoamide T was synthesized and provided to Aspergillus versicolor and Aspergillus sp. MF297-2, in which significant incorporation was observed in the advanced metabolite, notoamide B.
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59
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60
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Li S, Finefield JM, Sunderhaus JD, McAfoos TJ, Williams RM, Sherman DH. Correction to “Biochemical Characterization of NotB as an FAD-Dependent Oxidase in the Biosynthesis of Notoamide Indole Alkaloids”. J Am Chem Soc 2012. [DOI: 10.1021/ja3107753] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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61
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Li S, Anand K, Tran H, Yu F, Finefield JM, Sunderhaus JD, McAfoos TJ, Tsukamoto S, Williams RM, Sherman DH. Comparative analysis of the biosynthetic systems for fungal bicyclo[2.2.2]diazaoctane indole alkaloids: the (+)/(-)-notoamide, paraherquamide and malbrancheamide pathways. MEDCHEMCOMM 2012; 3:987-996. [PMID: 23213353 PMCID: PMC3511817 DOI: 10.1039/c2md20029e] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The biosynthesis of fungal bicyclo[2.2.2]diazaoctane indole alkaloids with a wide spectrum of biological activities have attracted increasing interest. Their intriguing mode of assembly has long been proposed to feature a non-ribosomal peptide synthetase, a presumed intramolecular Diels-Alderase, a variant number of prenyltransferases, and a series of oxidases responsible for the diverse tailoring modifications of their cyclodipeptide-based structural core. Until recently, the details of these biosynthetic pathways have remained largely unknown due to lack of information on the fungal derived biosynthetic gene clusters. Herein, we report a comparative analysis of four natural product metabolic systems of a select group of bicyclo[2.2.2]diazaoctane indole alkaloids including (+)/(-)-notoamide, paraherquamide and malbrancheamide, in which we propose an enzyme for each step in the biosynthetic pathway based on deep annotation and on-going biochemical studies.
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Finefield JM, Sherman DH, Kreitman M, Williams RM. Enantiomeric natural products: occurrence and biogenesis. Angew Chem Int Ed Engl 2012; 51:4802-36. [PMID: 22555867 PMCID: PMC3498912 DOI: 10.1002/anie.201107204] [Citation(s) in RCA: 201] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Indexed: 01/07/2023]
Abstract
In nature, chiral natural products are usually produced in optically pure form-however, occasionally both enantiomers are formed. These enantiomeric natural products can arise from a single species or from different genera and/or species. Extensive research has been carried out over the years in an attempt to understand the biogenesis of naturally occurring enantiomers; however, many fascinating puzzles and stereochemical anomalies still remain.
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63
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Pan G, Williams RM. Unified total syntheses of fawcettimine class alkaloids: fawcettimine, fawcettidine, lycoflexine, and lycoposerramine B. J Org Chem 2012; 77:4801-11. [PMID: 22519642 DOI: 10.1021/jo3006045] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The total syntheses of the lycopodium alkaloids fawcettimine, fawcettidine, lycoflexine, and lycoposerramine B have been accomplished through an efficient, unified, and stereocontrolled strategy that relies on a Diels-Alder reaction to construct the cis-fused 6,5-carbocycles with one all-carbon quaternary center. Access to the enantioselective syntheses of both antipodes of those alkaloids can be achieved by kinetic resolution of the earliest intermediate via a Sharpless asymmetric dihydroxylation (Sharpless AD). Compared to existing approaches to these alkaloids, our synthetic route possesses superior stereocontrol over the C-4 and C-15 stereogenic centers as well as allowing for more functional variation on the 6-membered ring.
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64
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Finefield JM, Sherman DH, Kreitman M, Williams RM. Enantiomere Naturstoffe: Vorkommen und Biogenese. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107204] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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65
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Guerra-Bubb J, Croteau R, Williams RM. The early stages of taxol biosynthesis: an interim report on the synthesis and identification of early pathway metabolites. Nat Prod Rep 2012; 29:683-96. [PMID: 22547034 DOI: 10.1039/c2np20021j] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The biosynthesis of the anti-cancer drug taxol (paclitaxel) has required the collaborative efforts of several research groups to tackle the synthesis and labeling of putative biosynthetic intermediates, in concert with the identification, cloning and functional expression of the biosynthetic genes responsible for the construction of this complex natural product. Based on a combination of precursor labeling and incorporation experiments, and metabolite isolation from Taxus spp., a picture of the complex matrix of pathway oxygenation reactions following formation of the first committed intermediate, taxa-4(5),11(12)-diene, is beginning to emerge. An overview of the current state of knowledge on the early-stages of taxol biosynthesis is presented.
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66
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Finefield JM, Frisvad JC, Sherman DH, Williams RM. Fungal origins of the bicyclo[2.2.2]diazaoctane ring system of prenylated indole alkaloids. JOURNAL OF NATURAL PRODUCTS 2012; 75:812-33. [PMID: 22502590 PMCID: PMC3485739 DOI: 10.1021/np200954v] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Over eight different families of natural products consisting of nearly 70 secondary metabolites that contain the bicyclo[2.2.2]diazaoctane ring system have been isolated from various Aspergillus, Penicillium, and Malbranchea species. Since 1968, these secondary metabolites have been the focus of numerous biogenetic, synthetic, taxonomic, and biological studies and, as such, have made a lasting impact across multiple scientific disciplines. This review covers the isolation, biosynthesis, and biological activity of these unique secondary metabolites containing the bridging bicyclo[2.2.2]diazaoctane ring system. Furthermore, the diverse fungal origin of these natural products is closely examined and, in many cases, updated to reflect the currently accepted fungal taxonomy.
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67
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McMullen JD, Kwan AC, Williams RM, Zipfel WR. Enhancing collection efficiency in large field of view multiphoton microscopy. J Microsc 2012; 241:119-24. [PMID: 21118215 DOI: 10.1111/j.1365-2818.2010.03419.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many multiphoton imaging applications would benefit from a larger field of view; however, large field of views (>mm) require low magnification objectives which have low light collection efficiencies. We demonstrate a light collection system mounted on a low magnification objective that increases fluorescence collection by as much as 20-fold in scattering tissues. This peripheral detector results in an effective numerical aperture of collection >0.8 with a 3-4 mm field of view.
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68
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Rafferty RJ, Williams RM. FORMAL SYNTHESIS OF HAPALINDOLE O AND SYNTHETIC EFFORTS TOWARDS HAPALINDOLE K AND AMBIGUINE A. HETEROCYCLES 2012; 86:219-231. [PMID: 24808627 DOI: 10.3987/com-12-s(n)3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The formal synthesis of D,L-hapalindole O has been accomplished intercepting Natsume's total synthesis route. The intercepted substrate was synthesized in an overall 36% yield over ten-synthetic steps compared to Natsume's overall 1% yield over eighteen-synthetic steps. In addition, advanced substrates for the continuing progress towards hapalindole K and ambiguine A has been synthesized. All routes described herein employ a novel silyl ether-based strategy accessing the 6:5:6:6 ring system, that has previously been used in our laboratory to access the total synthesis of D,L-hapalindoles J and U.
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69
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Schuber PT, Williams RM. Synthetic studies toward MPC1001: preparation of a β-hydroxyl-tyrosine derivative. Tetrahedron Lett 2012; 53:380-382. [DOI: 10.1016/j.tetlet.2011.11.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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70
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Schuber PT, Williams RM. SYNTHETIC STUDIES ON MPC1001: A DIPOLAR CYCLOADDITION APPROACH TO THE PYRROLIDINE RING SYSTEM. HETEROCYCLES 2012; 84:1193-1207. [PMID: 23667292 DOI: 10.3987/com-11-s(p)101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A novel [1,3]-dipolar azomethine ylide cycloaddition has been developed in an approach to the synthesis of the MPC1001 family of natural products.
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71
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Takahashi D, Izawa K, Kashiwagi T, Onoye H, M. Williams R. An Improved Synthesis of 5-Acylamino-6-oxo-2-phenyl-1(6H)-pyrimidineacetic Acid from Glycine with Readily Removable Protecting Groups. HETEROCYCLES 2012. [DOI: 10.3987/com-12-12518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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72
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73
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Li S, Finefield JM, Sunderhaus JD, McAfoos TJ, Williams RM, Sherman DH. Biochemical characterization of NotB as an FAD-dependent oxidase in the biosynthesis of notoamide indole alkaloids. J Am Chem Soc 2011; 134:788-91. [PMID: 22188465 DOI: 10.1021/ja2093212] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Notoamides produced by Aspergillus spp. bearing the bicyclo[2.2.2]diazaoctane core structure with unusual structural diversity represent a compelling system to understand the biosynthesis of fungal prenylated indole alkaloids. Herein, we report the in vitro characterization of NotB, which catalyzes the indole 2,3-oxidation of notoamide E (13), leading to notoamides C (11) and D (12) through an apparent pinacol-like rearrangement. This unique enzymatic reaction with high substrate specificity, together with the information derived from precursor incorporation experiments using [(13)C](2)-[(15)N](2) quadruply labeled notoamide S (10), demonstrates 10 as a pivotal branching point in notoamide biosynthesis.
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Abstract
The total synthesis of D,L-hapalindoles J and U has been accomplished. Hapalindole J was prepared in 11% overall yield over 11 synthetic steps and hapalindole U was prepared in 25% overall yield over 13 synthetic steps from commercially available materials. The route employs a novel silyl ether-based strategy for accessing the 6:5:6:6 ring system of the hapalindoles rapidly and in good yields.
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75
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Kato H, Nakamura Y, Finefield JM, Umaoka H, Nakahara T, Williams RM, Tsukamoto S. Study on the biosynthesis of the notoamides: Pinacol-type rearrangement of the isoprenyl unit in deoxybrevianamide E and 6-hydroxydeoxybrevianamide E. Tetrahedron Lett 2011; 52:6923-6926. [PMID: 22140281 DOI: 10.1016/j.tetlet.2011.10.065] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Two reverse-prenylated indole alkaloids, deoxybrevianamide E and 6-hydroxydeoxybrevianamide E, are proposed as biosynthetic precursors for advanced metabolites isolated from the marine-derived Aspergillus sp. In order to uncover the role of the alkaloids in the biosynthetic pathway, the feeding experiments of the [(13)C](2)-[(15)N]-labeled deoxybrevianamide E and 6-hydroxydeoxybrevianamide E were performed to afford the metabolites, which were produced by oxidation and successive pinacol-type rearrangement of the isoprenyl units.
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