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.
A variety of N-tosyl aziridines undergo ring opening with indium trihalides in acetonitrile at ambient temperature to afford the corresponding haloamines in excellent yields with high regioselectivity.
N-Allylanilines undergo 3-aza-Cope rearrangement in the presence of Zn2+ montmorillonite under microwave irradiation in the absence of solvent to afford indoline derivatives in high yields. Similarly arylallyl thioethers are rearranged to dihydrobenzothiophenes.
Trityl ethers are selectively cleaved by cerium(III) chloride in high yields in refluxing acetonitrile under neutral reaction conditions. The method is compatible with other acid sensitive functional groups like acetonide, acetate, benzoate, BOC, Cbz, benzyl, TBDPS, PMB, allyl, methyl and tetrahydropyranyl ethers present in the molecule.
Scandium(III) trifluoromethanesulfonate is found to catalyze efficiently the O-glycosidation of 3,4,6-tri-O-acetyl-d-glucal with various alcohols and phenols to afford the corresponding 2,3-unsaturated glycosides in excellent yields with good anomeric selectivity.