First Enantioselective Synthesis of (R)-Convolutamydine B and E with N-(Heteroarenesulfonyl)prolinamides

Enantioselective synthesis of (R)-convolutamydine B and E by the reaction of actaldehyde with ketones using organocatalysts was reported. The reaction of 4,6-dibromoisatin with acetaldehyde was examined in presence of various chiral organo-catalysts. The results show that the reaction sing TFA salt of N(p-toluene-sulfonyl)prolinamide rapidly produced to give (R)-convolutamydine B and E in high yield with 90% ee. The reaction of unsubstituted isatin with acetaldehyde gave product in good yield but with low enantioselectivity, the reaction of substituted isatins gave products with high enantioselectivity. The reaction of (R)-convolutamydine B and E with various aldehydes in the presence of 10% mol of N-(2-thiophenesulfonyl)prolinamide shows that the linear aldehydes afforded the products in high yield with good enentioselectivity.