Mukund G. Kulkarni

Wittig olefination: An efficient route for the preparation of allyl vinyl ethers - precursors for the Claisen rearrangement

Abstract A convenient procedure has been described for the preparation of allyl vinyl ethers-the precursors for the Claisen rearrangement

Chemoselective alkylation of L-ascorbic acid

Abstract A study on a general chemoselective method for the preparation of 3-O-alkyl and differentially protected 2.3-di-O-alkyl derivatives of 5,6-O-isopropylidene-L-ascorbic acid is described.

Allyl vinyl ethers via Wittig olefination: a short and efficient synthesis of (±)-mesembrine

Abstract A Wittig olefination-Claisen rearrangement approach has been successfully applied to a short and efficient synthesis of (±)-mesembrine.

AN EFFICIENT TOTAL SYNTHESIS OF ()-LAURENE

A short and efficient total synthesis of (±)-laurene using a Wittig olefination–Claisen rearrangement–Wacker oxidation protocol is described.

Total synthesis of (±)-coerulescine and (±)-horsfiline

Summary Wittig olefination–Claisen rearrangement protocol was applied to obtain 3-allyl oxindole. This oxindole was then converted to (±)-coerulescine and (±)-horsfiline.

Zeolite catalyzed solvent-free one-pot synthesis of dihydropyrimidin-2(1H)-ones - A practical synthesis of monastrol

Summary A zeolite-catalyzed, simple, one-pot, solvent-free, cost effective, and environmentally benign process for the synthesis of dihydropyrimidones is described. This reaction is scaleable to multigram scale and the catalyst is recyclable. This methodology has resulted in an efficient synthesis of monastrol, a potent inhibitor of kinesin Eg5.

The Paternò–Büchi Reaction of L‐Ascorbic Acid

Chiral oxetanes 1 are available in synthetically useful yields by the Paterno–Buchi reaction of L-ascorbic acid derivatives. New sugar derivatives are accessible through the ring-opening reactions of these oxetanes.

A Wittig-olefination-Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis.

Summary Efficient syntheses are described for the synthetically important 3-methylquinoline-4-carbaldehydes 6a–h from o-nitrobenzaldehydes 1a–h employing a Wittig-olefination–Claisen-rearrangement protocol. The Wittig reaction of o-nitrobenzaldehydes with crotyloxymethylene triphenylphosphorane afforded crotyl vinyl ethers 2a–h, which on heating under reflux in xylene underwent Claisen rearrangement to give 4-pentenals 3a–h. Protection of the aldehyde group of the 4-pentenals as acetals 4a–h and subsequent oxidative cleavage of the terminal olefin furnished nitroaldehydes 5a–h. Reductive cyclization of these nitroaldehydes yielded the required 3-methylquinoline-4-carbaldehydes 6a–h in excellent yields. Therefore, an efficient method was developed for the preparation of 3-methylquinoline-4-carbaldehydes from o-nitrobenzaldehydes in a simple five-step procedure.

Chemistry of L-ascorbic acid. Part 3. Photoreduction of quinones with 5,6-O-isopropylidene-L-ascorbic acid

Upon irradiation with UV light, instead of undergoing the Paterno–Buchi reaction, 5,6-O-isopropylidene-L-ascorbic acid reduced quinones quite efficiently and rapidly to the corresponding hydroquinones.

Wittig Olefination–Claisen Rearrangement Protocol for Cyclohexene Annulation

A two-step iterative sequence of Wittig olefination followed by Claisen rearrangement resulted in 1,7-octadienes, which afforded the corresponding cyclohexene carbaldehydes upon ring-closing metathesis with Grubbs catalyst.