In(OTf)3-catalyzed tandem aza-Piancatelli rearrangement/Michael reaction for the synthesis of 3,4-dihydro-2H-benzo[b][1,4]thiazine and oxazine derivatives

Abstract

Furan-2-yl(phenyl)methanol derivatives undergo smooth aza-Piancatelli rearrangement with 2-aminothiophenol and 2-aminophenol in the presence of 10 mol% In(OTf)₃ in acetonitrile at room temperature to afford the corresponding 3,4-dihydro-2H-benzo[b][1,4]thiazine or oxazine derivatives respectively in good yields with high selectivity in short reaction times. The salient features of this methodology are good yields, high selectivity, low catalyst loading and faster reaction times. The structure of the products was established by nOe studies and X-ray crystallography.