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Pure Appl. Chem., 2012, Vol. 84, No. 7, pp. 1597-1619

Published online 2012-05-22

Stereoselective construction of 5,11‑methanomorphanthridine and 5,10b‑phenanthridine structural frameworks: Total syntheses of (±)-pancracine, (±)‑brunsvigine, (±)-maritidine, and (±)-crinine

Ganesh Pandey* and Smita R. Gadre

Division of Organic Chemistry, National Chemical Laboratory, Pune-411008, India

Abstract: The core structure of the complex pentacyclic 5,11-methanomorphanthridine skeleton and the vicinal quaternary and tertiary stereocenters of the 5,10b-phenanthridine skeleton are constructed stereospecifically in one step employing intramolecular 1,3-dipolar cycloaddition of a nonstabilized azomethine ylide (AMY) generated by the sequential double desilylation of appropriate bis-trimethylsilylmethyl amines using Ag(I)F as a single-electron oxidant. The strategy is successfully applied for the total synthesis of biologically active alkaloids such as (±)-pancracine, (±)-brunsvigine, (±)-maritidine, and (±)-crinine.