1,2-Thiazines and benzo derivatives

Sulfur atoms can exhibit a valency of four allows the formation of 1-substituted 1, 2-thiazines with a double bond between two heteroatoms, and the second bond elsewhere in the ring. Although these compounds could be described as “dihydro derivatives,” they are isomeric with 1, 2-thiazines, in which the valency of the sulfur atom is two and there is no double bond between the heteroatoms. The compounds of 2H- and 3H, 6H-1, 2-thiazines and bicyclic 1, 2-thiazines are discussed. The literature containing the thermal stability of N-chlorosulfenyl-N-trimethylsilyl alkylamines increases with the size of the alkyl group. When thermolysed these compounds generate the corresponding N-sulfides (alkylN=S), which can be trapped by dienes—such as 2, 3-dimethyl-1, 3-butadiene, to give the 3, 6-dihydro-2H-1, 2-thiazines. These compounds are discussed with structural diagrams. The 1, 2-disposition of heteroatoms allows several different types of ring fusions for the general class of compounds containing benzo-1, 2-thiazines are briefly explained.