ENANTIOSPECIFIC SYNTHESES OF (R)-PROLINE AND (S)-PROLINE AND SOME DERIVATIVES FROM D-GLUCONO-1,5-LACTONE

Carbohydrate-based enantiospecific syntheses of (R)-proline 1 and (S)- proline 2 from the previously reported D-erythro-hexonate ester 9 are described, Azide-substitution reactions on appropriately activated int ermediates derived from ester 9, followed by reductive cyclization (H- 2/Pd-C), gave the substituted pyrrolidines 14 and 22, which were conve rted into their corresponding M-Cbz derivatives 16 and 24 in conventio nal manner. Mild acidic hydrolysis of these, followed by oxidation (so dium metaperiodate), gave the protected prolinals 3 and 4, which on fu rther oxidation (sodium chlorite), followed by catalytic hydrogenolysi s, gave the prolines 1 and 2, The N-Cbz-prolinol derivatives 5 and 6 a re also reported.