作者:Peter Langer、Wolf-Diethard Pfeiffer、Harald Roßberg、Nazken Kelzhanova、Alexander Villinger、Amanzhan T. Saginayev
DOI:10.3987/com-13-s(s)109
日期:——
Various 1,3,4-selenadiazines were prepared by cyclization of selenosemicarbazides with phenacyl bromides. The compounds generally exist in their 6H-tautomeric form and contain an exocyclic imino group in the solid state. 1,3,4-4H-Selenadiazines, available from 1,2-dimethylated selenosemicarbazides, cannot be isolated because they rapidly undergo a deselenation reaction under the conditions of their formation. Deselenation can be induced for 1,3,4-6H-selenadiazines under forcing conditions by reflux of a solution in glacial acetic acid. On the other hand, a ring contraction is observed when concentrated HCl or HBr is used.