48. Diastereoselective Spirocyclization of C-(Alkyloxycarbonyl)formimines of 2-Substituted 1H-Indole-3-ethanamines (= Tryptamines): Basic Studies

Article abstract of DOI:10.1002/hlca.19900730224

C-(Alkoxycarbonyl)formimines of type 15-18 were derived from the 2-substituted tryptamines 2, 9, 10, and 11 and transformed with tosyl chloride into tricyclic 3-spiroindoles of types 19-22 (Scheme 3).The influence of the homochiral alkoxy moieties A-D on the stereochemical outcome of this reaction was studied.Good-to-excellent diastereoselectivities were observed with the (-)-8-(phenylmenth-3-yl)oxy group (B) as homochiral auxiliary.The structures of the tricycles 4, (2'R,3S)-19B, and (2'S,3R)-20C were established by X-ray analysis, the structures of the others by NOE and CD studies, and by chemical correlation.Possibilities to explain the steric course of the spirocyclizations are discussed.