Structure-Activity Relationship Study of Biselyngbyolide B Reveals Mitochondrial Fission-Induced Cytotoxicity in Cancer.

A systematic structure-activity relationship study of the potent anticancer marine macrolide biselyngbyolide B has been accomplished. A total of 11 structural variants of the parent natural product, of which 2 are natural analogues, have been studied against a human colorectal carcinoma cell line. The requisite functional units of the parent molecule responsible for the cytotoxic activities have been disclosed.

Late-Stage Functionalization: Total Synthesis of Beauveamide A and Its Congeners and Their Anticancer Activities.

Asymmetric 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.

Total synthesis and stereochemical assignment of bipolamide A acetate.

Asymmetric 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.

Cyclodepsipeptide alveolaride C: total synthesis and structural assignment.

First stereoselective total synthesis of naturally occurring bioactive cyclodepsipeptide alveolaride C has been achieved using a convergent approach. This synthetic study enabled us to establish unambiguously the stereochemistry of three unassigned chiral centres embedded in the nonpeptidic segment as well as revised the stereochemistry of the proposed β-phenylalanine counterpart of the molecule. The key strategic features of this synthesis include Sharpless asymmetric dihydroxylation for installing the vicinal diol moiety, Julia-Kocienski olefination for constructing the aliphatic side chain, the Shiina protocol for intermolecular esterification, amide coupling and macrolactamization for the ring formation.

Total synthesis: the structural confirmation of natural products.

This feature article highlights total synthesis as one of the reliable tools for the structural confirmation of natural products. Even though there has been substantial improvement in spectroscopic techniques that has opened an important avenue up to the synthetic community for discoveries, the structural misassignment of natural products remains a common occurrence. Herein, we have included a few case studies, along with some selected examples of natural products associated with our current research interests, where structures were revised in recent years using the art of chemical synthesis.

Total Synthesis of Pestalotioprolide E and Structural Revision of Pestalotioprolide F.

A short and convergent strategy for the first asymmetric total synthesis of cytotoxic macrolides pestalotioprolides E and F has been developed. The key features of this synthesis include Takai olefination, Sonogashira coupling, Ni-assisted partial hydrogenation of alkyne, modified Steglich reaction to generate the ester moiety, and intramolecular Horner-Wadsworth-Emmons (HWE) olefination to complete the macrocycle. This synthetic study revised the proposed structure of pesralotioprolide F.