General approach for the total synthesis of the sarpagine related indole alkaloids (+)-Na-methyl-16-epipericyclivine, (-)-alkaloid Q3 and (-)-panarine via the asymmetric Pictet-Spengler reaction

The stereospecific total synthesis of (+)-N-a-methyl-16-epipericyclivine (1) was completed [from D-(+)-tryptophan methyl ester] in an overall yield of 42% (eight reaction vessels). The optical rotation {[alpha](D) +22.8 (c 0.50, CHCl3)} obtained on this material confirmed that the reported optical rotation {[alpha](D) 0 (c 0.50, CHCl3)} was biogenetically unreasonable. The first total synthesis of (-)-alkaloid Q(3) (5) and (-)-panarine (6), via the intermediate vellosimine (18), is also described. (C) 2002 Elsevier Science Ltd. All rights reserved.