ASYMMETRIC-SYNTHESIS OF ENANTIOPURE ALPHA-SULFENYL DITHIOACETALS AND ALPHA-SULFENYL ALDEHYDES

The BF3.Et2O promoted thiolytic cleavage of the diastereomeric oxazolidines (1'R)-2 and (1'S)-2 has been studied. The thioacetalisations took place with concomitant thioetherification at the carbinol centres, giving rise to the a-sulfenyl dithioacetals (alpha-SDTA's) (S)-3 and (R)-3 respectively. Selective manipulation of the latter compounds was also achieved. Thus, oxidative hydrolysis gave the corresponding alpha-sulfenyl aldehydes which were shown to be enantiopure.