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Namba K, Kaihara Y, Yamamoto H, Imagawa H, Tanino K, Williams RM, Nishizawa M. Toward palau'amine: Hg(OTf)2-catalyzed synthesis of the cyclopentane core. Chemistry 2009; 15:6560-3. [PMID: 19492366 PMCID: PMC2837586 DOI: 10.1002/chem.200900622] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractCatalytic cyclization: The Hg(OTf)2‐catalyzed N‐selective cyclization of amide carbonyl moieties for the construction of a quaternary carbon center was developed. The Hg(OTf)2‐catalyzed cyclization of cyclopentylidene alcohol with acylhydrazide afforded the desired cyclopenta[c]pyridazinone in good yield. The subsequent eight steps gave the functionalized cyclopentane with the correct stereochemistry that corresponds to the E ring of palau′amine (see scheme).magnified image
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102
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Williams RM, Burnett CM. New Tricks in Amino Acid Synthesis: Applications to Complex Natural Products. ACS SYMPOSIUM SERIES. AMERICAN CHEMICAL SOCIETY 2009; 1009:420-442. [PMID: 20563264 PMCID: PMC2886987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report the application of diphenyloxazinone glycinate chiral templates to asymmetric syntheses of cylindrospermospin, 7-epi-cylindrospermopsin, 7-deoxycylindrospermopsin, and spirotryprostatins A and B. Synthetic studies toward quinine, nakadomarin A, and palau'amine using these templates are also described.
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103
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Tsukamoto S, Kato H, Greshock TJ, Hirota H, Ohta T, Williams RM. 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 2009; 131:3834-5. [PMID: 19292484 DOI: 10.1021/ja810029b] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Notoamide E was identified to be a short-lived precursor in the biosynthesis of prenylated indole alkaloids in the mussel-derived Aspergillus sp. In addition, the feeding experiment of the (13)C-labeled notoamide E afforded structurally novel metabolites.
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104
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English BJ, Williams RM. Synthesis of (+/-)-Oleocanthal via a Tandem Intramolecular Michael Cyclization-HWE Olefination. Tetrahedron Lett 2009; 50:2713. [PMID: 20161637 PMCID: PMC2817976 DOI: 10.1016/j.tetlet.2009.03.145] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A synthesis of racemic oleocanthal has been accomplished in eleven steps from 1,3 propanediol by a key tandem intramolecular Michael cyclization-Horner Wadsworth Emmons olefination.
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105
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Miller KA, Tsukamoto S, Williams RM. Erratum: Asymmetric total syntheses of (+)- and (−)-versicolamide B and biosynthetic implications. Nat Chem 2009. [DOI: 10.1038/nchem.195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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106
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Bowers AA, West N, Newkirk TL, Troutman-Youngman AE, Schreiber SL, Wiest O, Bradner JE, Williams RM. Synthesis and histone deacetylase inhibitory activity of largazole analogs: alteration of the zinc-binding domain and macrocyclic scaffold. Org Lett 2009; 11:1301-4. [PMID: 19239241 DOI: 10.1021/ol900078k] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fourteen analogs of the marine natural product largazole have been prepared and assayed against histone deacetylases (HDACs) 1, 2, 3, and 6. Olefin cross-metathesis was used to efficiently access six variants of the side-chain zinc-binding domain, while adaptation of our previously reported modular synthesis allowed probing of the macrocyclic cap group.
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107
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Tsukamoto S, Kawabata T, Kato H, Greshock TJ, Hirota H, Ohta T, Williams RM. Isolation of antipodal (-)-versicolamide B and notoamides L-N from a marine-derived Aspergillus sp. Org Lett 2009; 11:1297-300. [PMID: 19281134 DOI: 10.1021/ol900071c] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antipodal (-)-versicolamide B and notoamides L-N were isolated from a marine-derived Aspergillus sp. The possible biosynthetic pathway of enantiomeric pairs of notoamide B and versicolamide B are proposed. Notoamide L is the first metabolite containing 25 carbons in the related prenylated indole alkaloids. Notoamide M is potentially a precursor to the proposed azadiene species involved in the putative intramolecular Diels-Alder reaction in the biogenesis of the bicyclo[2.2.2]diazaoctane ring system.
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108
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Chamberland S, Grüschow S, Sherman DH, Williams RM. Synthesis of potential early-stage intermediates in the biosynthesis of FR900482 and mitomycin C. Org Lett 2009; 11:791-4. [PMID: 19161340 DOI: 10.1021/ol802631c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Beyond the identification of 3-amino-5-hydroxybenzoic acid (AHBA) and D-glucosamine as biosynthetic precursors to mitomycin C (5) and FR900482 (6), little is known about the pathway Nature uses to prepare these antitumor antibiotics. To gain some insight into their biosynthesis, amino acids 1 and 2 as well as C-2 N-acetylated derivatives 3 and 4 were prepared. Preparation of these putative biosynthetic intermediates and N-acetylcysteamine thioester analogues 28 and 29 should enable confirmation of their involvement in FR900482 and mitomycin C biosynthesis.
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109
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Artman GD, Rafferty RJ, Williams RM, Aaron GL, Davis MM, Brummond KM. (3R,7aS)-3-(TRICHLOROMETHYL)TETRAHYDROPYRROLO[1,2-C]OXAZOL-1(3H)-ONE: AN AIR AND MOISTURE STABLE REAGENT FOR THE SYNTHESIS OF OPTICALLY ACTIVE α-BRANCHED PROLINES. ORGANIC SYNTHESES; AN ANNUAL PUBLICATION OF SATISFACTORY METHODS FOR THE PREPARATION OF ORGANIC CHEMICALS 2009; 86:262. [PMID: 21331348 PMCID: PMC3039172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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110
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Fishlock D, Williams RM. Synthetic studies on Et-743. Assembly of the pentacyclic core and a formal total synthesis. J Org Chem 2008; 73:9594-600. [PMID: 18687003 PMCID: PMC2736329 DOI: 10.1021/jo801159k] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A formal total synthesis of the potent anticancer agent Et-743 is described. The tetrahydroisoquinoline core is stereoselectively constructed using a novel radical cyclization of a glyoxalimine. Further elaboration of this core rapidly accessed the pentacyclic core of Et-743, but a mixture of regiosisomers was obtained in the key Pictet-Spengler ring closure. A known advanced intermediate in the synthesis of Et-743 was intercepted, constituting a formal synthesis of the molecule.
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111
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Miller KA, Figueroa M, Valente MWN, Greshock TJ, Mata R, Williams RM. Calmodulin inhibitory activity of the malbrancheamides and various analogs. Bioorg Med Chem Lett 2008; 18:6479-81. [PMID: 18986806 PMCID: PMC2629606 DOI: 10.1016/j.bmcl.2008.10.057] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 10/10/2008] [Accepted: 10/13/2008] [Indexed: 10/21/2022]
Abstract
The preparation and biological activity of various structural analogs of the malbrancheamides are disclosed. The impact of indole chlorination, C-12a relative stereochemistry, and bicyclo[2.2.2]diazaoctane core oxidation state on the ability of these analogs to inhibit calmodulin dependent phosphodiesterase (PDE1) was studied, and a number of potent compounds were identified.
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112
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Ding Y, Greshock TJ, Miller KA, Sherman DH, Williams RM. Premalbrancheamide: synthesis, isotopic labeling, biosynthetic incorporation, and detection in cultures of Malbranchea aurantiaca. Org Lett 2008; 10:4863-6. [PMID: 18844365 PMCID: PMC2651399 DOI: 10.1021/ol8019633] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An advanced metabolite, named premalbrancheamide, involved in the biosynthesis of malbrancheamide (1) and malbrancheamide B (2) has been synthesized in double (13)C-labeled form and was incorporated into the indole alkaloid 2 by Malbranchea aurantiaca. In addition, premalbrancheamide has been detected as a natural metabolite in cultures of M. aurantiaca. The biosynthetic implications of these experiments are discussed.
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113
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Ding Y, Gruschow S, Greshock TJ, Finefield JM, Sherman DH, Williams RM. Detection of VM55599 and preparaherquamide from Aspergillus japonicus and Penicillium fellutanum: biosynthetic implications. JOURNAL OF NATURAL PRODUCTS 2008; 71:1574-8. [PMID: 18754595 PMCID: PMC2834492 DOI: 10.1021/np800292n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The secondary metabolites VM55599 (4) and preparaherquamide (5) have been identified by LC-MS(n) analysis as natural metabolites in cultures of Penicillium fellutanum, whereas preparaherquamide has been identified only in cultures of Aspergillus japonicus. In accord with a previous proposal, the identification of both metabolites, which have a diastereomeric relationship, provides indirect support for a unified biosynthetic scheme.
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114
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Bowers A, West N, Taunton J, Schreiber SL, Bradner JE, Williams RM. Total synthesis and biological mode of action of largazole: a potent class I histone deacetylase inhibitor. J Am Chem Soc 2008; 130:11219-22. [PMID: 18642817 PMCID: PMC3090445 DOI: 10.1021/ja8033763] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The efficient total synthesis of the recently described natural substance largazole (1) and its active metabolite largazole thiol (2) is described. The synthesis required eight linear steps and proceeded in 37% overall yield. It is demonstrated that largazole is a pro-drug that is activated by removal of the octanoyl residue from the 3-hydroxy-7-mercaptohept-4-enoic acid moiety to generate the active metabolite 2, which is an extraordinarily potent Class I histone deacetylase inhibitor. Synthetic largazole and 2 have been evaluated side-by-side with FK228 and SAHA for inhibition of HDACs 1, 2, 3, and 6. Largazole and largazole thiol were further assayed for cytotoxic activity against a panel of chemoresistant melanoma cell lines, and it was found that largazole is substantially more cytotoxic than largazole thiol; this difference is attributed to differences in the cell permeability of the two substances.
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115
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Horiguchi T, Rithner CD, Croteau R, Williams RM. Studies on Taxol® Biosynthesis. Preparation and Tritium Labeling of Biosynthetic intermediates by Deoxygenation of a Taxadiene Tetra-acetate Obtained from Japanese Yew. J Labelled Comp Radiopharm 2008; 51:325-328. [PMID: 20221307 DOI: 10.1002/jlcr.1529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Taxa-4(20),11(12)-diene-5α-acetate 5 and Taxa-4(20), 11(12)-diene-5α-acetate, 10β-ol 6, have been identified as early stage intermediates involved in the biosynthesis of Taxol® (paclitaxel). Tritium-labeled 5 and 6 were successfully prepared by Barton deoxygenation using tri-n-butyltintritiide of the C-14-hydroxyl group of a taxoid obtained from Japanese Yew.
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116
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Almerie MQ, Williams RM, Acerini CL. Should Angiotensin converting enzyme inhibitors be used in children with type 1 diabetes and microalbuminuria? Arch Dis Child 2008; 93:633-5. [PMID: 18285389 DOI: 10.1136/adc.2008.138982] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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117
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Sommer K, Williams RM. Studies Towards Paraherquamides E & F and Related C-labeled Putative Biosynthetic Intermediates: Stereocontrolled Synthesis of the α-Alkyl-β-Methylproline Ring System. Tetrahedron 2008; 64:7106-7111. [PMID: 20336192 DOI: 10.1016/j.tet.2008.05.068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A substituted 2R-allyl-3S-methylproline ethyl ester suitable for elaboration to paraherquamides E, F and related (13)C-labelled putative biosynthesis intermediates have been prepared efficiently in six steps and 24% overall yield. The key steps are a 5-exo-trig cyclization of a zinc enolate on an unactivated alkene and a stereocontrolled alkylation of the enolate formed from 3S-methyl-pyrrolidine-1,2R-dicarboxylic acid 1-tert-butyl ester 2-ethyl ester.
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118
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Greshock TJ, Grubbs AW, Jiao P, Wicklow DT, Gloer JB, Williams RM. Isolation, structure elucidation, and biomimetic total synthesis of versicolamide B, and the isolation of antipodal (-)-stephacidin A and (+)-notoamide B from Aspergillus versicolor NRRL 35600. Angew Chem Int Ed Engl 2008; 47:3573-7. [PMID: 18389509 DOI: 10.1002/anie.200800106] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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119
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Miller KA, Welch TR, Greshock TJ, Ding Y, Sherman DH, Williams RM. Biomimetic total synthesis of malbrancheamide and malbrancheamide B. J Org Chem 2008; 73:3116-9. [PMID: 18345688 PMCID: PMC2837585 DOI: 10.1021/jo800116y] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biomimetic total syntheses of both malbrancheamide and malbrancheamide B are reported. The synthesis of the two monochloro species enabled the structure of malbrancheamide B to be unambiguously assigned. The syntheses each feature an intramolecular Diels-Alder reaction of a 5-hydroxypyrazin-2(1H)-one to construct the bicyclo[2.2.2]diazaoctane core, which has also been proposed as the biosynthetic route to these compounds.
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120
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Ding Y, Williams RM, Sherman DH. Molecular analysis of a 4-dimethylallyltryptophan synthase from Malbranchea aurantiaca. J Biol Chem 2008; 283:16068-76. [PMID: 18390548 DOI: 10.1074/jbc.m801991200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prenyltransferases are widely distributed in prokaryotes and eukaryotes and play critical roles in cell signaling, protein trafficking, and elaboration of complex molecules in secondary metabolism. Numerous prenylated natural products have been isolated from diverse microorganisms, including bacteria and fungi. These complex metabolites possess a wide range of biological activities, with some showing promise as medicinal agents. On the other hand, many prenylated secondary metabolites have been described as toxins such as ergot alkaloids that have potent psychotropic activity. We have characterized a new prenyltransferase isolated from genomic DNA of Malbranchea aurentiaca RRC1813. Enzyme specificity was investigated with a series of amino acid substrates revealing its function as a 4-dimethylallyltryptophan synthase. Polypeptide sequence alignment analysis showed that it groups with a new class of prenyltransferase enzymes that lack the typical (N/D)DXXD motif found in these polypeptides. MaPT activity was not dependent on a divalent cation cofactor, although it was reversibly inactivated by 5 mm EDTA. Analysis of kinetic parameters showed reduced enzyme efficiency upon simple modification of l-Trp. Moreover, d-Trp had 0.5% relative activity and functioned as a competitive inhibitor with a K(i) of 40.41 microm. Finally, Thr-105, Asp-179, Lys-189, and Lys-261 in MaPT were serially mutated, and the resulting lesions displayed low or complete loss of activity. This study provides a detailed characterization of a prenyltransferase in Malbranchea species, reveals two enzyme inhibitors, and through site-directed mutagenesis identified several key amino acid residues in catalysis, yielding new insights into this important yet understudied class of natural product biosynthetic enzymes.
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Iles R, Williams RM, Deeb A, Ross-Russell R, Acerini CL, Acerini CL. A longitudinal assessment of the effect of inhaled fluticasone propionate therapy on adrenal function and growth in young children with asthma. Pediatr Pulmonol 2008; 43:354-9. [PMID: 18286548 DOI: 10.1002/ppul.20770] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Fluticasone proprionate (FP) is increasingly used to treat very young children with asthma. Its safety in terms of effects on the hypothalamic pituitary axis (HPA) and growth in this age group is uncertain. PATIENTS AND METHODS Eleven children (median (range) age 10 (5.6-24.3) months) presenting with recurrent wheeze and family history of asthma were studied prospectively for a period of 18 months. Children received daily-inhaled FP 250 microg via a spacer device. No other corticosteroid therapy was administered prior to or during the study. A Short Standard Synacthen Test (SST) (125 microg) was performed pretreatment, and after 6 and 18 months. Weight (Wt), height (Ht), and body mass index (BMI) were measured at 3-6 monthly intervals. RESULTS Fasting early morning and peak cortisol levels remained within the normal reference range with therapy. There were no changes in Ht SDS, whereas both Wt SDS (baseline 0.05 (-2.17 to 0.52) vs. +18 months 0.68 (-0.5 to 1.36) P < 0.02) and BMI SDS (-0.22 (-1.73 to 0.75) vs. 0.86 (0.03 to 1.99) P < 0.005) increased after 18 months of treatment. CONCLUSION Daily treatment with inhaled FP 250 microg in young children with asthma appears to have no adverse effects on the HPA or on linear growth, however, treatment is associated with increases in body Wt and BMI in young children.
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Smith AC, Williams RM. Rabe rest in peace: confirmation of the rabe-kindler conversion of D-quinotoxine into quinine: experimental affirmation of the Woodward-Doering formal total synthesis of quinine. Angew Chem Int Ed Engl 2008; 47:1736-40. [PMID: 18236503 DOI: 10.1002/anie.200705421] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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123
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Greshock TJ, Johns DM, Noguchi Y, Williams RM. Improved total synthesis of the potent HDAC inhibitor FK228 (FR-901228). Org Lett 2008; 10:613-6. [PMID: 18205373 DOI: 10.1021/ol702957z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A scaleable synthesis of the potent histone deacetylase (HDAC) inhibitor FK228 is described. A reliable strategy for preparing the key beta-hydroxy mercapto heptenoic acid partner was accomplished in nine steps and 13% overall yield. A Noyori asymmetric hydrogen-transfer reaction established the hydroxyl stereochemistry in >99:1 er via the reduction of a propargylic ketone.
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124
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Namiki H, Chamberland S, Gubler DA, Williams RM. Synthetic and biosynthetic studies on FR900482 and mitomycin C: an efficient and stereoselective hydroxymethylation of an advanced benzazocane intermediate. Org Lett 2007; 9:5341-4. [PMID: 18047354 DOI: 10.1021/ol701960v] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report a simple, efficient, and stereoselective Mukaiyama aldol approach to install the key hydroxymethyl moiety into the benzazocane framework of FR900482. Synthetic investigations revealed that the reaction is highly dependent upon the electronics of the aromatic ring. This approach enabled the economical introduction of a [13C] label to study the biosynthesis of these structurally and biogenetically related natural products. Epimerization of the initially formed beta-hydroxy ketone may enable access to mitomycin C or FR900482 biosynthetic congeners.
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125
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Abstract
The direct conversion of beta-hydroxyproline derivatives into 5-hydroxypyrazin-2(1H)-ones under Mitsunobu conditions has been discovered to be a general biomimetic protocol generating IMDA intermediates and has been applied to the concise, biomimetic total syntheses of D,L-stephacidin A and D,L-brevianamide B.
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