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.
Synthesis of thiol esters from acyl chlorides and thiols in the presence of activated zinc is described. The recovery of zinc and its reuse makes the procedure more economic.
A simple, efficient, stereo- and regio-selective method for the synthesis of optically active 2-azido-1-phenylethanols by asymmetric reduction of 2-azidoacetophenones with in situ generated, oxazaborolidine-borane complexes in THF, is described. This new method appears to be an alternative to the classical methods previously reported.