One-Pot Synthesis of 1-Substituted 1H-Isochromenes by Combining Brønsted Acid with Silver Catalysis

A one-pot synthesis of 1-substituted 1 H -isochromenes employing various 2-alkynyl-benzaldehydes and ketones as substrates under a combination of Bronsted acid and silver catalysis has been developed. The isochromenes, which are present as important heterocyclic core structures in many bioactive and natural compounds, are obtained in medium to excellent yields with diastereomeric ratios of up to 9:1. A first enantioselective variant has also been tested.