Enantioselective synthesis of threo-α,β-dihydroxyphosphonates by asymmetric dihydroxylation of 1(E)-alkenylphosphonates with AD-mix reagents
摘要:
Asymmetric dihydroxylation (AD) of 1(E)-alkenylphosphonates with an AD-mix -alpha or -beta reagent was examined to give a series of optically active threo-alpha,beta-dihydroxyphosphonates. Good enantioselectivity (>88% eel was observed in the AD reaction of 1(E)-alkenylphosphonates with conjugated aromatic substituents. The steric effects of the ester functionality in the course of the dihydroxylation were also evaluated. Enantioselectivity and yield were significantly improved when the AD reaction was carried out with dimethyl phosphonate instead of diethyl phosphonate. (C) 1997 Elsevier Science Ltd. All rights reserved.
Enantioselective synthesis of threo-α,β-dihydroxyphosphonates by asymmetric dihydroxylation of 1(E)-alkenylphosphonates with AD-mix reagents
摘要:
Asymmetric dihydroxylation (AD) of 1(E)-alkenylphosphonates with an AD-mix -alpha or -beta reagent was examined to give a series of optically active threo-alpha,beta-dihydroxyphosphonates. Good enantioselectivity (>88% eel was observed in the AD reaction of 1(E)-alkenylphosphonates with conjugated aromatic substituents. The steric effects of the ester functionality in the course of the dihydroxylation were also evaluated. Enantioselectivity and yield were significantly improved when the AD reaction was carried out with dimethyl phosphonate instead of diethyl phosphonate. (C) 1997 Elsevier Science Ltd. All rights reserved.
Enantioselective synthesis of threo-α,β-dihydroxyphosphonates by asymmetric dihydroxylation of vinylphosphonates. An application to the stereocontrolled synthesis of (4S,5S)-4-diethylphosphono-5-hydroxymethyl-2,2-dimethyl-1,3-dioxolane
The asymmetricdihydroxylation (AD) reaction of vinylphosphonates with AD-mix-α and -β reagents was successfully applied to the enantioselective synthesis of threo-α, β-dihydroxyphosphonates. β-Aryl substituents on the vinyl phosphonates were found to be good directors for the reaction with respect to the yield and enantioselectivity. The utility of chiral α, β-dihydroxyphosphonate 2c was illustrated