A quinidine-catalyzed diastereoselective addition of α-angelica lactone to β-halo-α-ketoesters is reported. The α-angelica lactone displays unusual regioselectivity in this reaction, acting as a nucleophile at the α-position to provide fully substituted glycolic esters with three contiguous stereocenters. Subsequent diastereoselective hydrogenation provides an additional stereocenter within the lactone
据报道,
奎尼丁对β-卤代-α-
酮酸酯的α-
当归内酯具有非对映选择性。α-
当归内酯在该反应中表现出异常的区域选择性,在α-位上充当亲核试剂,以提供具有三个连续的立体中心的完全取代的
乙醇酸酯。随后的非对映选择性氢化在内酯内提供了另外的立体中心。