Three-Component Site-Selective Synthesis of Highly Substituted 5<i>H</i>‑Chromeno-[4,3‑<i>b</i>]pyridines

An efficient and concise one-pot procedure was developed based on a cascade reaction of 3-formylchromones <b>1</b> and different types of 1,1-enediamines (EDAMs) <b>2</b> with different alcohols or amines <b>3</b> by a site-selective synthesis of 5<i>H</i>-chromeno­[4,3-<i>b</i>]­pyridines in an environmentally friendly solvent. This protocol is especially suitable for the efficient and rapid parallel synthesis of 5<i>H</i>-chromeno­[4,3-<i>b</i>]­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