G.V.M. Sharma

Efficient Room‐Temperature Synthesis of Tri‐ and Tetrasubstituted Imidazoles Catalyzed by ZrCl4

Abstract A general protocol has been developed for the rapid synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles in high yields using ZrCl4 as an efficient catalyst at room temperature. A variety of aromatic, aliphatic, and terpenoidal aldehydes underwent condensation with NH4OAc/amines to give the imidazoles. Similarly, the imidazole glycoconjugates are prepared in good yields from the corresponding glycosyl aldehydes. IICT Communication No. 051119.

An effective practical method for the synthesis of chiral propargyl alcohols

Abstract The preparation of chiral propargyl alcohols (2) is described by LiNH2 or LDA induced double elimination of chiral epoxychlorides (4) derived from their corresponding epoxyalcohols (3) which are available easily by Sharpless asymmetric epoxidation of the primary allyl alcohols. Whereas use of stoichiometiric amount of base on 4 provides chirally enriched trans -1-chlorovinyl alcohols (14).

Tetra-n-butylammonium fluoride: an efficient base for aza-Michael addition—synthesis of glycosyl β-amino acid esters

A mild and efficient route to glycosyl β-amino acid esters, exploiting the stereoselective Michael addition of benzylamine, in the presence of tetra-n-butylammonium fluoride, to sugar derived γ-alkoxy α,β-unsaturated esters is described.

Mn(OAc)3—an efficient oxidant for regeneration of DDQ: deprotection of p-methoxy benzyl ethers

Abstract Mn(OAc) 3 has been successfully developed as a new oxidant for the regeneration of DDQ from HDDQ. This DDQ regeneration technique, making use of 3 equiv. of Mn(OAc) 3 –DDQ (10 mol%), was applied to the deprotection of p -methoxy benzyl (PMB) ethers.

Asymmetric Baylis-Hillman reaction using sugar acrylates-synthesis of optically active α-methylene-β-hydroxy alkanoates

Abstract A study on the asymmetric Baylis–Hillman reaction of three chiral acrylates; 1,2:5,6-di- O - iso -propylidine-α- d -glucofuranose-3-acrylate 1 , 2,3:5,6-di- O - iso -propylidine-α- d -mannofuranose-1-acrylate 2 and 1,2- O - iso -propylidine-5- O - tert -butyldimethylsilyl-α- d -xylofuranose-3-acrylate 3 , with various aldehydes was conducted, resulting in adducts with moderate diastereoselectivity (5–40% e.e.).

Yb(OTf)3/FeCl3 mediated facile conversion of alcohols, ketals and acid sensitive ethers into diphenylmethyl (DPM) ethers ☆

10 mol% Yb(OTf)3 or FeCl3 have been developed as efficient reagents for the conversion of alcohols into diphenylmethyl (DPM) ethers. Similarly, FeCl3 has also been advantageously utilised to successfully convert ketals and acid sensitive ethers into DPM ethers.

A simple and efficient PdCl2 mediated conversion of γ,δ-olefinic alcohols into C-glycosides

Abstract An efficient and mild intramolecular oxidative nucleophilic cyclisation protocol has been developed for the conversion of γ, δ-olefinic alcohols into the hemiketals, which in turn on deoxygenation led to the very important C-glycoside class of compounds.

A stereoselective synthesis of coriolic acid and dimorphecolic acid

Abstract Described herein is a convenient synthesis of coriolic acid ( 1 ) and dimorphecolic acid ( 2 ), the two natural ionophores derived respectively from bovine heart mitochondria and also shown to be self defensive substances in rice plant against rice blast disease.

STEREOSELECTIVE SYNTHESIS OF (-)-CANADENSOLIDE FROM D-GLUCOSE

Abstract A simple and stereoselective synthesis of (−)-canadenosolide starting from D-glucose, through a radical mediated cyclisation, has been described.

A simple and stereoselective synthesis of avenaciolide from D-glucose

Abstract A stereoselective synthesis of avenaciolide starting from D-glucose, involving intramolecular radical cyclisation, has been described.