1-Cyano-P-carboline

The pyrrolinyl- (6-11) and pyrrolyl-substituted (12-13) eudistomin skeletons were first prepared by Rinehart from 1-cyano-P-carboline (145), which can be obtained from the corresponding acid (28). Grignard reaction with appropriately protected 3-bromopropanal (Scheme 4) provided the necessary carbons with appropriate oxidation level for cyclization to either of these ring systems. The pyrrolyl-substituted eudistomins then result upon hydrolysis of the imine and acetal functions with concomitant cyclization in the presence of ammonia. The pyrrolinyl-eudistomins require reduction of the imine to the amine followed by acetal hydrolysis and simultaneous ring closure to isomer 147. Reduction of the imine 147 followed by allylic oxidation with sodium hypochlorite isomerizes 147 to the pyrrolinyl-eudistomin skeleton (149). 

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