Stereoselective epoxidation of asymmetrized 2-alkenyl-1,3-propanediols.
摘要:
Asymmetrized 2-alkenyl 1,3-propanediols are stereoselectively epoxidized to the same main diastereoisomer both with 3-chloroperbenzoic acid and the VO(acac)2/t-butyl hydroperoxyde system. Using the latter epoxidating reagent in combination with a protection-deprotection sequence involving the two homoallylic hydroxy groups, all the four cis epoxides were easily achieved in stereoisomeric pure form starting from a single common (Z) precursor.
Stereoselective epoxidation of asymmetrized 2-alkenyl-1,3-propanediols.
摘要:
Asymmetrized 2-alkenyl 1,3-propanediols are stereoselectively epoxidized to the same main diastereoisomer both with 3-chloroperbenzoic acid and the VO(acac)2/t-butyl hydroperoxyde system. Using the latter epoxidating reagent in combination with a protection-deprotection sequence involving the two homoallylic hydroxy groups, all the four cis epoxides were easily achieved in stereoisomeric pure form starting from a single common (Z) precursor.
Cis epoxides of any desired absolute stereochemistry have been obtained in a high enantio- and diastereodivergent manner via diastereospecific epoxidation of asymmetrized (Z)-2-alkenyl-1,3-propanediols, in turn obtained through a chemoenzymatic route, and a protection-deprotection ‘trick’ on hydroxy groups.