Three-Component Site-Selective Synthesis of Highly Substituted 5 H-Chromeno-[4,3- b]pyridines.

An efficient and concise one-pot procedure was developed based on a cascade reaction of 3-formylchromones 1 and different types of 1,1-enediamines (EDAMs) 2 with different alcohols or amines 3 by a site-selective synthesis of 5 H-chromeno[4,3- b]pyridines in an environmentally friendly solvent. This protocol is especially suitable for the efficient and rapid parallel synthesis of 5 H-chromeno[4,3- b]pyridine compounds. It also has some advantages, such as convenience of operation, short reaction times, use of a green solvent, and ease of purification by washing the crude products with ethanol.