Convenient synthesis of 1,2-dihydroquinoline-3-carboxylic acid and 2H-1-benzothiopyran-3-carboxylic acid derivatives
Abstract
A new and efficient method for the preparation of 1,2-dihydroquinoline-3-carboxylic acid derivatives via a magnesium amide-induced sequential conjugate addition–aldol type condensation reaction between 2-(alkylamino)phenyl ketones and α,β-unsaturated carboxylic acid derivatives, followed by simple dehydration, is described. The method can be applied to the synthesis of 2H-1-benzothiopyran-3-carboxylic acid derivatives using 2-mercaptobenzophenone in place of 2-(alkylamino)phenyl ketones.