V. R. Mamdapur

Stereoselective and versatile approach for the synthesis of gossyplure and its components

Abstract Efficient synthetic routes to gossyplure and its components (1a and 1b) were formulated. The three key units viz the alkynol 3, the bromide 5, and the alkanal 13 were derived from easily accessible starting materials. Alkylation of 3 with 5, and subsequent semihydrogenation followed by oxidation, provided the C11-alkenal 8 which was subjected to a stereocontrolled Wittig reaction with a C5-phosphonium salt, to yield directly the desired pheromone (1a + 1b). The synthesis of its individual components involved the manipulation via an acetylenic intermediate, viz the alkynol 14 which was obtained through alkylation of 3. A sequence of well-established reactions on 14, then provided the corresponding (E)- and (Z)-alkenylphosphonium salts which upon a (Z)-specific Wittig olefination with the C7-aldehyde (13), led to the stereoselective synthesis of 1a and 1b.

A new convenient approach to peptide synthesis using a diselenide and a phosphine

Abstract A new and highly efficient method based on a redox reaction using diphenyl diselenide and tributylphosphine for the general synthesis of peptides is described. The side reaction due to selenophenol formation is overcome by using chalcone as a scavenger or by selective oxidation to diselenide.

Synthesis of both the enantiomers of 4-dodecanolide, the pheromone of the rove beetle

Abstract A simple and efficient synthesis of the target pheromone in its enantiomeric forms has been formulated using easily accessible (R)-2,3- isopropanedioxyglyceraldehyde (2) as the single starting chiron.

C-21 Steroids in the defensive secretions of some Indian water beetles—II

Abstract From the defensive secretions of water beetles Cybister limbatus, C. tripunctatus and C. confusus, a number of C-21 steroids viz. Δ4-pregnen-12β-ol-3,20-dione (I), Δ4,6-pregnadien-12β-ol-3,20-dione (II), Δ4-presnen-20β-ol-3-one (III), and Δ4-pregnen-21-ol-3,20-dione (IV) have been isolated and characterized.

Chiral Synthesis of Trogodermal, the Pheromone of Dermestid Beetles

Abstract The title pheromone, (R)-14-Methyl-8-(Z and E)-hexadecen-1-al (Ia and Ib) have been synthesised following a simple route using (R)-pulegone as the starting chiron.

One pot amide/ peptide synthesis via two redox reactions

Abstract A new and highly efficient one-pot self-regulated approach to amide/ peptide synthesis has been developed based on two redox reactions using azide as a latent amine component. For the first time, selenophenol, generated in situ has been found to be an effective reducing agent for the conversion of azides to amines.

Cyclopentanoid allylsilanes in synthesis of di- and triquinanes. A stereoselective synthesis of (±)-hirsutene

Abstract A new general route to cis -1,2-disubstituted cyclopentanoid allylsilanes is described based on intramolecular ene reaction of activated 1,6-dienes featuring a homoallylsilane unit as the ene donor. In addition, application of these allylsilanes to the synthesis of some di- and triquinanes including the fungal metabolite (±)- hirsutene is presented.

Cyclopentanoid allylsilanes in synthesis : A stereoselective synthesis of (+)-hirsutene

Abstract A formal total synthesis of the mold metabolite ( + )-hirsutene is described from the cyclopentanoid allylsilane 3 where the key step utilizes an epoxy-allylsilane ring closure.

A Convenient Synthesis of (r)-Japonilure

Abstract The title pheromone has been synthesised in high optical purity using easily accessible (S)-glycerol-2, 3-acetonide (2) as the starting chiron.

PPL catalyzed monoesterification of α,ω-dicarboxylic acids

SummaryA regioselective strategy for PPL catalysed monoesterification of aliphatic α,ω-dicarboxylic acids with n-butanol have been developed. In addition to high regioselectivity, the method also ensures chemoselective esterification of a saturated acid moiety in presence of a conjugated acid function.