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Synthesis 2007(2): 225-230  
DOI: 10.1055/s-2006-958938
PAPER
© Georg Thieme Verlag Stuttgart · New York

A Convenient Access to 3-(Trihalomethyl)-3-phenyl-3,4-dihydro-2H-1,4-benz­oxazines/thiazines and Chlorinated 3-Phenyl-2,3-dihydro-1,5-benzoxazepines/thiazepines by an Aziridination-Selective-Ring-Opening Sequence

Ekaterina Yu. Shinkevich, Mikhail S. Novikov, Alexander F. Khlebnikov*
Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Petrodvorets, Russian Federation
Fax: +7(812)4286939; e-Mail: Alexander.Khlebnikov@pobox.spbu.ru;
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Publication History

Received 4 September 2006
Publication Date:
14 December 2006 (online)

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Abstract

Aziridine ring opening with N-C(1) bond breaking in 1,1-dichloro-1a-phenyl-1a,2-dihydro-1H-azirino[2,1-c][1,4]benz­oxazine and -benzothiazine proceeds under the action of hydrohalo acid to give 3-trihalomethyl derivatives of 1,4-benzoxazine and thiazine. When the same compounds react with boron trifluoride etherate, the ring expansion with N-C(1a) bond breaking takes place with formation of 3,4-dichloro-3-phenyl-2,3-dihydro-1,5-benzoxazepine and -1,5-benzothiazepine. These are convenient precursors for the synthesis of 4-substituted 1,5-benzoxazepine and 1,5-benzothiazepine derivatives via reaction with nucleophiles.

Key words

fused haloaziridines - O,N-heterocycles - S,N-heterocycles - ring expansion - dihalocarbenes - acid catalysis