1,4-Thiazines, 1,4-benzothiazines phenothiazines and related compounds

This review is based upon the literature covered in chemical abstracts from 1986 to 1996; however, some duplication of synthetic methodologies was found to be necessary, still these routes are much in use. The synthesis of compounds for 3, 4-dihydro-2H-1, 4-thiazines and 5, 6-dihydro-4H-1, 4-thiazines are presented with structural illustrations. The process involved in obtaining 1, 4-thiazines (perhydro 1, 4-thiazines) are explained for the resulting compound with figures. The chapter contains information on 1, 4-benzothiazines and related compounds are discussed. The section on phenothiazines describes the traditional methods used to obtain these heterocycles. An illustration of the use of carbon dioxide to protect and then activate the adjacent center shows that phenothiazine is N-deproronated by butyllithium at -78 oC in THF and N-lithium derivative, may then be reacted with CO₂ to give lithium carboxalate.The literature contains information related to phenothiazian-3-one syntheses, based upon the condensation reactions of quinones and the related compounds with 2-aminothiophenols.