T. Ramalingam

Microwave-assisted efficient synthesis of dihydro pyrimidines: improved high yielding protocol for the Biginelli reaction

Dihydropyrimidines were synthesised in high yields by one-pot cyclocondensation reaction of aldehydes, aceto-acetates and urea using various acid catalysts like Amberlyst-15, Nafion-H, KSF clay and dry acetic acid under microwave irradiation.

A MILD AND EFFICIENT CLEAVAGE OF gem-DIACETATES TO ALDEHYDES BY CBr4 *

gem-Diacetates are selectively deprotected to the corresponding aldehydes in high yields by CBr4 in refluxing acetonitrile under neutral reaction conditions. *IICT Communication No. 4491.

Solvent-Free Conversion of N,N-Dimethylhydrazones to Nitriles Under Microwave Irradiation

Abstract A variety of aldehyde N,N-dimethylhydrazones are rapidly converted into the corresponding nitriles using oxone supported on wet Al2O3 under microwave irradiation in dry media.

Microwave-accelerated synthesis of 4-chlorotetrahydropyrans by bismuth(III) chloride

ABSTRACT The cross-coupling reaction of homoallyl alcohols with aldehydes in the presence of bismuth trichloride in solvent-free conditions generated 4-chloro-2,6-disubstituted tetrahydropyrans in high yields with high diastereoselectivity. Improved yields and reduced reaction times are achieved in this transformation by employing microwave irradiation. * IICT Communication No. 4702.

KF-Al2O3 MEDIATED CROSS-CANNIZZARO REACTION UNDER MICROWAVE IRRADIATION*

ABSTRACT Aromatic aldehydes are selectively converted to the corresponding alcohols in high yields by cross-Cannizzaro reaction using KF-Al2O3 under microwave irradiation in solvent-free condition. *IICT Communication No. 4420.

BISMUTH(III) CHLORIDE CATALYZED AZA-DIELS-ALDER REACTION*

Bismuth (III) chloride effectively catalyzes aza-Diels-Alder reaction of N-aryl aldimines with nucleophilic olefins for the first time to afford quinoline derivatives in high yields at ambient temperature. *IICT Communication No. 4499.

Short-route synthesis of (3E,5Z)-tetradecadienoic acid (megatomic acid), the sex attractant of the black carpet beetle

A new and expeditious route to (3E,5Z)-3,5-tetradecadienoic acid (megatomic acid), the sex attractant of the black carpet beetle Attagenus megatoma (Fabricius), is reported which proceeds with 97% stereoselectivity; Cadiot–Chodkiewicz cross-coupling of 1-decyne and 4-bromo-3-butyn-1-ol in the presence of CuCl, followed by stereoselective reductions and Jones oxidation, gives the target molecule, with the synthetic pheromone showing a positive electrophysiological response.

An efficient and selective conversion of hydrazides into esters and acids

Hydrazides are selectively oxidised to esters/acids in high yields using Oxone® in the presence of an appropriate alcohol/water as a nucleophile at ambient temperature. A variety of functional groups including alkenes, alcohols, ethers, cyclopropyl groups and nitriles are unaffected.

Metal triflates catalyzed efficient synthesis of 3,4-dihydro-2H-1-benzopyrans

Ytterbium triflate efficiently catalyzes an unusual cyclization of o-hydroxybenzaldehydes with 2,3-dihydrofuran and 3,4-dihydro-2H-pyran in the presence of trimethyl orthoformate at ambient temperature to afford a new class of compounds, furo- and pyrano[2,3-b]benzopyrans in excellent yields with high diastereoselectivity. Also, o-hydroxybenzaldehydes reacted smoothly with acetophenones in the presence of a catalytic amount of scandium triflate under similar reaction conditions to give the corresponding 2,4-dialkoxy-2-aryl-3,4-dihydro-2H-1-benzopyrans in high yields.