Chemoselective reactions of carbonyl compounds using trimethylsilyl triflate

Abstract

The chemoselective allylation of carbonyl compounds via sulfonium salts has been investigated. Reaction of an equimolar mixture of an aldehydo group and a keto group with dimethyl sulfide and trimethylsilyl trifluoromethanesulfonate affords selective allylation of the aldehydo group in high yields but the reaction between aldehydo group and cyclohexanone shows a moderate chemoselectivity. High chemoselectivities have been Enones and ketones. Chemoselective reactions of acyclic acetals in the presence of cyclic acetals have been studied. Allylation, cyanation and azidation of acyclic acetals in the presence of cyclic acetals of ketones and aldehydes using trimethylsilyl trifluoromethanesulfonate have been achieved higher selectivities and yields than those using other Lewis acid ($TiCl_4$, $BF_3\cdot OE_2$) at low temperature.