Asymmetric Hydrogenation of In Situ Generated Isochromenylium Intermediates by Copper/Ruthenium Tandem Catalysis

Abstract

Abstract The first asymmetric hydrogenation of in situ generated isochromenylium derivatives is enabled by tandem catalysis with a binary system consisting of Cu(OTf) 2 and a chiral cationic ruthenium–diamine complex. A range of chiral 1 H ‐isochromenes were obtained in high yields with good to excellent enantioselectivity. These chiral 1 H ‐isochromenes could be easily transformed into isochromanes, which represent an important structural motif in natural products and biologically active compounds. The chiral induction was rationalized by density functional theory calculations.