Synthesis of spiroindolenine-bearing chroman scaffolds based on a cyclization reaction of para-Quinone methides

Abstract

An efficient diastereoselective cyclization reaction of ortho-hydroxyphenyl-substituted para-quinone methides with α,β-unsaturated imines generated in situ from aryl sulfonyl indoles was developed, and afforded spiroindolenine-bearing chroman scaffolds in good to excellent yields (up to 98%) and diastereoselectivities (up to >19 : 1 d.r.). This protocol provided an efficient method for constructing spirocyclic compounds incorporating two pharmacophores, namely chroman and spiroindoline.