A NOVEL DEOXYGENATION OF HYDROXY-GROUPS ACTIVATED BY A VICINAL CARBONYL GROUP VIA REACTION WITH PH3P I-2/IMIDAZOLE/

A new procedure for a direct conversion of an alpha-hydroxy sugar este r, lactone or amide into the corresponding alpha-deoxyester , lactone or nitrile using the system Ph-3/I-2 /imidazole is reported. Its effic iency is illustrated by deoxygenation in good yields at position 2 of methyl 3,4:5,6-di-O-isopropylidene-D-gluconate (1), and at positions 5 of l-1,2-O-isopropylidene-alpha-D-glucofuranuronamide (3) and isoprop ylidene-alpha-D-glucofuranurono-6,3-lactone (5). Reaction with 5,6-O-i sopropylidene-L- and -D-gulo-1,4-lactones (7) and (9), respectively, a fforded the corresponding alpha,beta-unsaturated lactones in good yiel ds.