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Paper | Special issue | Vol 56, No. 1-2, 2002, pp.379-385
Published online, 1st January, 1970
DOI: 10.3987/COM-01-S(K)53
Regioselectivity in the Schmidt Reaction: First Synthesis of Pyrano[3,2-b]azepines

Franc Pozgan, Slovenko Polanc, and Marijan Kočevar*

*Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, SI-1000 Ljubljana, Slovenia

Abstract

The Schmidt reaction of 5,6,7,8-tetrahydro-2H-1-benzopyran-2-ones (1) has been investigated. Derivatives of pyrano[3,2-c]azepines (2) and isomeric pyrano[3,2-b]azepines (3) were isolated by the application of trimethylsilyl azide or sodium azide in a methylene chloride or a chloroform solution in the presence of sulfuric acid. At low temperature products (2) were almost sole products, while at higher temperature derivatives (3) were also isolated in reasonable yields. Derivatives of pyrano[3,2-c]pyridines (5) can be prepared from cyclopenta[b]pyran-2,5-diones (4) employing the same method.