Synthesis 2006(2): 261-272  
DOI: 10.1055/s-2005-918513
PAPER
© Georg Thieme Verlag Stuttgart · New York

Reactions of Unsaturated Azides; Part 17: [1] An Efficient Strategy for the Synthesis­ of Small-Ring Heterocycles via Isomerization of 2-Halo-2H-azirines

Joseph Rodolph Fotsing, Klaus Banert*
Chemnitz University of Technology, Institute of Chemistry, Organic Chemistry, Strasse der Nationen 62, 09111 Chemnitz, Germany
Fax: +49(371)5311839; e-Mail: klaus.banert@chemie.tu-chemnitz.de;
Further Information

Publication History

Received 5 April 2005
Publication Date:
21 December 2005 (online)

Abstract

New acceptor-substituted allenyl halides were synthesized. The addition of hydrazoic acid (HN3) to these allenyl halides led to the formation of new 1-azido-2-haloethene derivatives. The photolysis of the latter compounds afforded the corresponding 2-halo-2H-azirines. At room temperature or below, they isomerized irreversibly by [1,2]-rearrangement of halogen to form other azirine isomers in very good yields. It is the first time that such a complete rearrangement of 2-halo-2H-azirines is observed. This synthetic strategy offers the possibility to observe both azirine isomers in their pure forms from single 1-azido-2-haloethene precursor.

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An alleged 2-methylene-2H-azirine [14] proved to be a structurally isomeric product. [15]