Synthetic Applications of 2-(1,3-Dithian-2-yl)indoles. IV. New Synthesis of the Tetracyclic ABED Ring System of Strychnos Alkaloids

Article abstract of DOI:10.1016/S0040-4020(01)89689-7

A new and versatile synthesis of tetracyclic compounds 10, 22 and 24 presenting the ABED ring system of Strychnos alkaloids is described by closure of the C₁-C_11b bond in the key step.The intermediate tetrahydropyridinium salts 2 have been obtained from 2-(1,3-dithian-2-yl)indole (3) and either 2-cyano-3-ethyl-1-methyl-1,2,3,6-tetrahydropyridine (4a) or N-substituted Δ³-piperidein-2-ones (5).