Optional Diastereo‐ and Enantioselective Synthesis of Vicinal threo ‐ or erythro ‐Dihydroxy Derivatives

A possibility of obtaining the desired diastereomer of compounds containing the 1,2‐di‐ O structural element was realized with the isopropylidene‐protected ( R )‐glyceraldehyde 1a . Compound 1a can be converted >90% threo ‐ or erythro ‐selectively into the β‐alkoxycarboxylates 2 / 3 . For the preparation of 2 , the method of choice is the addition of diallylzinc followed by Lemieux cleavage, whereas the best route from 1a to 3 is via the aryl ester 1b and the addition of alkoxide to 1b . 2 and 3 can be converted into the lactones 4 and 5 , respectively.