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A Catalytic Diastereoselective Formal [5+2] Cycloaddition Approach to Azepino[1,2‐ a ]indoles: Putative Donor–Acceptor Cyclobutanes as Reactive Intermediates
Author(s) -
Shenje Raynold,
Martin M. Cynthia,
France Stefan
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201408429
Subject(s) - cyclobutanes , cycloaddition , cyclobutane , alkene , chemistry , intramolecular force , lewis acids and bases , catalysis , amide , azepine , ketene , ring (chemistry) , medicinal chemistry , stereochemistry , organic chemistry
A catalytic formal [5+2] cycloaddition approach to the diastereoselective synthesis of azepino[1,2‐ a ]indoles is reported. The reaction presumably proceeds through a Lewis acid catalyzed formal [2+2] cycloaddition of an alkene with an N ‐indolyl alkylidene β‐amide ester to form a donor–acceptor cyclobutane intermediate, which subsequently undergoes an intramolecular ring‐opening cyclization. Azepine products are formed in up to 92 % yield with high degrees of diastereoselectivity (up to 34:1 d.r.).