Regioselectivity in the Schmidt Reaction: First Synthesis of Pyrano3,2-bAzepines

摘要

The Schmidt reaction of 5,6,7,8-tetrahydro-2H-1-benzoopyran-2-ones (1) has been investigated. Derivatives of pyrano3,2-cazepines (2) and isomeric pyrano3,2-bazepines (3) were isolated by the application of trimethylsilyl azide or soduim 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 isoalted in reasonable yields. Derivatives of pyrano3,2-cpyridines (5) can be prepared from cyclopentabpyran-2,5-diones (4) employing the same method.