Synthesis of new fused isoquinolines via reissert compounds

✍ Scribed by Christian Fuchs; Christoph Bender; Burkhard Ziemer; Jürgen Liebscher

• Book ID: 102892980
• Publisher: Journal of Heterocyclic Chemistry
• Year: 2008
• Tongue: English
• Weight: 669 KB
• Volume: 45
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570450615

✦ Synopsis

Abstract

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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.