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Synthesis of new fused isoquinolines via reissert compounds
Author(s) -
Fuchs Christian,
Bender Christoph,
Ziemer Burkhard,
Liebscher Jürgen
Publication year - 2008
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570450615
Subject(s) - chemistry , alkylation , isoquinoline , moiety , enamine , ring (chemistry) , alcohol , reagent , stereochemistry , medicinal chemistry , organic chemistry , catalysis
Reissert compounds 2 derived from isoquinoline, chloroformates and TMS‐cyanide were alkylated in position 1. The resulting alkylation products 3 as well as the precursors 2 reacted with Grignard reagents affording imidazoisoquinolines 4, 5, 7 and 8 by addition to the cyano group and Grignard reduction or by twofold addition to the cyano group, respectively. In both cases the alcohol of the 2‐alkoxycarbonyl moiety was eliminated by attack of the N‐atom at the carbonyl carbon atom. Under acid conditions, 1‐benzylated Reissert compound 3h cyclised by attack of the resulting N‐acyliminium C‐atom at the o ‐position of the benzyl ring to form tetracyclic 1,3‐bridged tetrahydroisoquinolines 10 and 11. Bromocyclisation of 1‐allyl‐2‐menthyloxycarbonyl‐substituted Reissert compounds 3b, c led to tricyclic dibromo products 12, in which the menthol moiety was split off and addition to the enamine double bond occurred. A 2‐menthyloxycarbonyl group in Reissert compounds 2a and 3 failed to exert an asymmetric induction in all cases.