MODELS OF FOLATE COENZYMES-VIII AN APPROACH TO YOHIMBANE ALKALOIDS VIA CARBON-FRAGMENT TRANSFER FROM N5,N10-METHYLENETETRAHYDROFOLATE MODELS

Article abstract of DOI:10.1016/S0040-4020(01)90904-4

2-Substituted 1-tosyl-3,4,4-trimethylimidazolidines, prepared by the addition of anions to 1-tosyl-3,4,4-trimethyl-2-imidazolinium iodide 1, react with tryptamine in the presence of acetic acid to give 1-substituted β-carboline derivatives.The salt 1 reacts with anions of 2-<2-(1,3-dithianyl)benzoates 4a-c to give the corresponding imidazolidines 5a, 5b and 5c, respectively.These transfer the substituted fragment(<*>CHR) to tryptamine to give pentacyclic products corresponding to the yohimbane skeleton.The product from 5c yields, after reduction of both the amide and the dithiane function, the precursor of epi- and allo-yohimbanes.