Enantiospecific total synthesis of the enantiomer of the indole alkaloid intermediate macroline

The total synthesis of the enantiomer 3En of macroline 3 was completed (from L-tryptophan methyl ester 6) in an overall yield of 12.3% (11 isolated intermediates). The corresponding macroline equivalent 18 was prepared in 14.3% yield. This work provides, for the first time, an opportunity to synthesize mismatched bisindole alkaloids for studies on the mechanism, of action of Alstonia antimalarial alkaloids at the receptor level. (C) 2002 Elsevier Science Ltd. All rights reserved.