The first stereocontrolled synthesis of 12-methylhexahydrobenzo[c]phenanthridine alkaloids

12-Methyl B/C hexahydrobenzo[c]phenanthridines have been synthesized stereo selectively starting from chiral nonracemic 2-aryl-4-pentenoic acids prepar ed by asymmetric allylation of (+)-(S,S)-pseudoephedrine-based arylacetamid e enolates. Subsequent transformations (Friedel-Crafts acylation, stereocon trolled reductive amination, Pictet-Spengler cyclization and PPA catalyzed cationic cyclization) led to the synthesis of enantiomerically enriched hex ahydrobenzo[c] phenanthridines in which the sequential formation of all the new stereogenic centres was controlled by the starting chiral acids. (C) 1 999 Elsevier Science Ltd. All rights reserved.