Facile Synthesis of 4-Substituted 3-Exo-methylenechroman Derivatives via Radical Cyclization Starting from Salicylaldehydes

摘要

Synthesis of 4-substituted 3-exo-methylenechroman derivatives was carried out by the n-Bu3SnH-mediated vinyl radical cyclization as the key step starting from various salicylaldehydes.The family of 1-benzopyran subunits such as chromans,2H-chromenes,and 4H-chromenes represents an important family of oxygen-containing natural products and showed many interesting biological activities.