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Diastereoselective Spirocyclization of C ‐(Alkyloxycarbonyl)formimines of 2‐Substituted 1 H Indole‐3‐ethanamines (= Tryptamines): Basic Studies. 5th Communication on Indoles, Indolenines, and Indolines
Author(s) -
Freund Ralf,
Mahboobi Siavosh,
Noack Klaus,
Schonhölzer Peter,
Bernauer Karl
Publication year - 1990
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19900730224
Subject(s) - tryptamines , chemistry , steric effects , stereochemistry , indole test , medicinal chemistry , tryptamine , biochemistry
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 ,3 S )‐ 19B , and (2′ S ,3 R ) 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.