Department of Biochemistry

Carbohydrate acetonides were chemoselectively cleaved to the corresponding diols by using environmentally benign phosphomolybdic acid (H3PMo12O40) supported on silica gel (PMA-SiO2) at ambient temperature in a short span of 5-7 minutes in acetonitrile. Acid-labile protective groups such as THP, TBS, TBDPS, MOM, OMe and PMB were found to be stable under the reaction conditions.

A novel one pot condensation of an aldehyde, β-ketoester and urea has been performed using TMSI in acetonitrile for the first time at room temperature affording dihydropyrimidinones in excellent yields.

Epoxides react smoothly with potassium thiocyanate in the presence of 5 mol% of indium tribromide under mild and convenient reaction conditions to afford the corresponding thiiranes in high yields. This method is compatible with a wide range of protecting groups and functional groups such as alkenes, alkynes, esters, THP, TBDMS, and PMB ethers present in the molecule.

Indoles react smoothly with terminal epoxides in the presence of catalytic amount of InCl3 under mild conditions to afford the corresponding 3-alkyl indole derivatives in high yields with high regioselectivity.

Lithium tetrafluoroborate is found to be an efficient catalyst for the chemoselective protection of both aromatic and aliphatic aldehydes as 1,3-oxathiolanes and 1,3-dithianes under mild reaction conditions. Due to the neutral reaction conditions, this method is compatible with acid sensitive substrates.

Lithium perchlorate in diethylether (LPDE) is found to catalyze imino-Diels-Alder reactions of N-aryl aldimines with 3,4-dihydro-2H-pyran (DHP), indene, and cyclohexenone to afford the corresponding pyrano, indeno quinolines and phenanthridinone derivatives in high yields.

α-Aminophosphonates are synthesized by three component condensation of aldehydes, amines and diethyl phosphite using montmorillonite KSF under microwave irradiation in solvent-free conditions to afford enhanced yields and reduced reaction times compared to conventional methods.

Scandium triflate catalyzes efficiently the allylation reactions of acetals and gem-diacetates with allyltrimethylsilane at ambient temperature to afford the corresponding homoallyl ethers and acetates in high yields. Also it is found to be effective for the direct formation of homoallyl ethers from aldehydes and allylsilane in presence of trimethylorthoformate.

Electron-rich arenes undergo electrophilic amination with diethyl azodicarboxylate on the surface of silica gel impregnated with indium trichloride in solvent-free conditions to afford para-substituted aryl hydrazides. Improved yields and enhanced rates are obtained by employing microwave irradiation.

Iodine efficiently catalyzes the glycosidation of glycals with allyltrimethylsilane, trimethylsilyl cyanide and trimethylsilyl azide in dichloromethane at ambient temperature to afford the corresponding 2,3-unsaturated allyl glycosides, glycosyl cyanides and glycosyl azides in excellent yields with high α-selectivity.