The stereoselective synthesis of the northern hemisphere (C-C) of the purported structure of the extremely potent anticancer natural product neaumycin B has been accomplished. Twelve out of nineteen asymmetry centers have been installed chemically. The key highlights of this synthesis include the Krische iridium catalyzed -diastereoselective carbonyl crotylation, the Crimmins aldol reaction, HWE olefination, CBS reduction, vanadium promoted stereoselective epoxidation, Evans methylation and spiroketalization.
View Article and Find Full Text PDFA convergent strategy for the first total synthesis of the lipopeptide bacilotetrin C has been developed. The key features of this synthesis include Crimmins acetate aldol, Steglich esterification, and macrolactamization. Twenty-nine variants of the natural product were prepared following a systematic structure-activity relationship study, where some of the designed analogues showed promising cytotoxic effects against multiple human carcinoma cell lines.
View Article and Find Full Text PDFAsymmetric total synthesis of cyclotetradepsipeptide beauveamide A has been achieved for the first time. A macrolactamization strategy involving two possible sites has been explored to find the most effective route for cyclization. A late-stage functionalization approach has been adopted for easy access of non-natural analogues of beauveamide A for further biological evaluation.
View Article and Find Full Text PDFAsymmetric total synthesis of an acetate analogue of the endophytic unstable secondary metabolite bipolamide A has been achieved for the first time adopting a convergent approach. The key feature of this synthesis includes Evans's asymmetric ethylation, Wittig olefination, Takai olefination, stereoselective Grignard addition and intermolecular Heck coupling. This eventually developed a synthetic route of the rarely found branched amine bearing an acyloin moiety.
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