O-Vinylphosphonylated Salicylaldehydes as Aldo-Vinyl Bifunctional Building Blocks for anti-3,4-Disubstituted Phosphadihydrocoumarins

An efficient synthetic strategy for anti-3,4-disubstituted phosphadihydrocoumarin compounds has been established by tandem aza-Michael–aldol-like annulations of tetrahydroisoquinolines with O-vinylphosphonylated salicylaldehydes as an aldo-vinyl bifunctional building block. This conversion was characterized by ‘green’ properties such as a step- and atom-economy, catalyst-free conditions, highly anti-selectivity­, and readily available starting materials.