V. Shekhar

Stereoselective synthesis and biological evaluation of (R)-rugulactone, (6R)-((4R)-hydroxy-6-phenyl-hex-2-enyl)-5,6-dihydro-pyran-2-one and its 4S epimer

A simple and highly efficient synthetic route has been developed for synthesis of (R)-rugulactone (1a), (6R)-((4R)-hydroxy-6-phenyl-hex-2-enyl)-5,6-dihydro-pyran-2-one (1b) and its 4S epimer 1c by employing proline-catalyzed alpha-aminooxylation, Sharpless epoxidation, Mitsunobu reaction as chirality introuducing steps. The antibacterial and antifungal activity of the compounds 1a, 1b and 1c were evaluated. 1a and 1b showed better antibacterial activity against Pseudomonas aeroginosa (MIC=12.5 microg/ml for 1a, 25 microg/ml for 1b) Klebsiella pneumonia (MIC=25 microg/ml for 1a). Compounds (1a, 1b, 1c) exhibited good to moderate antifungal activity.

Stereoselective total synthesis of (−)-cleistenolide

Abstract A stereoselective total synthesis of (−)-cleistenolide ( 1 ) derived from d -(−)-isoascorbic acid has been described. The new synthetic strategy involves highly diastereoselective reduction, one-pot protection of required benzoyl, acetyl groups, and the RCM reaction by using Grubbs catalyst are the key steps with considerable yields.

Stereoselective first total synthesis, confirmation of the absolute configuration and bioevaluation of botryolide-E.

A simple, first stereoselective total synthesis of botryolide-E has been described. The synthesis started from propylene oxide employing Jacobsens hydrolytic kinetic resolution (HKR), selective epoxide opening, sharpless asymmetric dihydroxylation, one pot acetonide deprotection and lactonization as key steps. Further, the synthesis confirms the absolute configuration of the natural product botryolide-E and we evaluated the biological behavior of natural product botryolide-E against a panel of bacteria and fungi. Botryolide-E exhibits significant potent activity against Staphylococcus aureus (MTCC 96) (6.25 μg/ml), good against Escherichia coli (MTCC 443) (12.5 μg/ml), Bacillus subtilis (MTCC 441) (25 μg/ml) and compound 1 exhibited good to moderate antifungal activity.

Stereoselective synthesis of alpinoid-C and its analogues and study of their cytotoxic activity against cancer cell lines.

A simple, highly efficient and stereoselective synthetic route has been developed for synthesis of alpinoid-C (1) and its analogues (2, 3 and 4) from commercially available starting materials by using Wittig olefination, Sharpless asymmetric epoxidation, Grubbs cross metathesis as key steps. All the compounds showed moderate anti-proliferative activity against human leukemia/carcinoma (U-937, THP-1, COLO-205 and HepG2) and mouse melanoma (B16-F10) cancer cell lines. Compounds 3 and 4 are found to be most potent with an IC(50) of 7.53 μM and 32.26 μM on THP-1, 11.12 μM and 7.21 μM on COLO-205 cell lines, respectively.

Concise Stereoselective Total Synthesis of (4R, 6R)-Lactone Moiety Analog of Mevinoline and Compactin

Abstract A simple and highly efficient synthetic route has been developed for analogue of HMGCo A reductase inhibitor (1). The strategy utilizes S-Corey–Bakshi–Shibata (CBS) reduction, FeCl3-catalyzed C-H insertion of ethyl diazoacetate. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] GRAPHICAL ABSTRACT