Knoevenagel‐Friedel‐Crafts‐Hemiketalization Triple Cascade Reaction: A Diastereoselective Formal [1+2+3] Cyclization Towards Indenonaphthopyran Scaffolds

Abstract

Abstract A simple and efficient cascade reaction via formal [1+2+3] cyclization of 1,3‐indanedione, aldehyde and 2‐naphthol is reported using K 2 CO 3 as a base. The advantage includes metal‐free conditions, varied substrate scope and shortened reaction duration with high diastereoselectivity (i. e., 99 : 1) resulting in the formation of two carbon‐carbon as well as two carbon‐oxygen bonds through Knoevenagel‐Friedel‐Crafts‐Hemiketalization sequence resulting in three contiguous stereocenters.