The total synthesis of 3,4,5,6-tetradehydro-17-hydroxycorynanium [(+)-4], the zwitterionic structure assigned to an alkaloid from Aspidosperma marcgravianum, has been accomplished for the first time via a "lactim ether route". The route started with an initial condensation between the lactim ether [(+)]-5] and 3-chloroacetylindole and proceeded through the lactam ester [(+)-23], lactam alcohol [(+)-24], acetoxylactam [(+)-26], quaternary iminium salt [(+)-25], and 3,4,5,6-tetradehydro-17-hydroxycorynanium perchlorate [(+)-27]. The1H NMR spectral data and the sign of specific rotation for the synthetic (+)-4 were in disagreement with those reported for a natural sample, leaving the chemistry of this A. marcgravianum alkaloid incomplete. © 1993.
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