Asymmetric synthesis of β-hydroxy acid via stereoselective dirhodium(II)-catalyzed C-H insertion of α-alkoxydiazoketone

A new methodology for the asymmetric synthesis of β-hydroxy acid was developed. Dirhodium(II)-catalyzed C-H insertion of α-alkoxydiazoketone (3), which was prepared from primary alkyl halide (1) and readily available chiral α-hydroxy acid (2), gave stereoselectively 2,5-cis-disubstituted 3(2H)-furanone (4). The Baeyer-Villiger reaction of 4 followed by treatment with an acid afforded chiral β-hydroxy acid (6) with high optical purity.