1, 3-Oxazines and Related Compounds. VII. Unusual Dimerization of 2-Alkyl-4H-1, 3-thiazin-4-one Derivatives and the Structures of the Dimers

Abstract

2-Alkyl-4H-1, 3-thiazin-4-one derivatives (1) were readily dimerized on being allowed to stand at room temperature, leading to linearly combined dimers. In addition, the 1, 3-thiazines (1) were found to be converted into another type of dimer, having a novel spiro structure, by the action of an acid such as CF₃CO₂H, ClSO₃H, or FSO₃H. The structures of the dimers were elucidated.