The Effective Synthesis of N-(Arylalkyl)-1-R-4-hydroxy-2,2-dioxo-1,2-dihydro-2λ6,1-benzothiazine- 3-carboxamides as Promising Analgesics of a New Chemical Class

A new, effective preparative method has been proposed and the synthesis of a series of N-(arylalkyl)-1-R-4-hydroxy-2,2-dioxo-1H-2λ(6),1-benzothiazine-3-car-boxamides has been carried out. It has been shown that amidation of alkyl 1-R-4-hydroxy-2,2-dioxo-1H-2λ(6),1-benzothiazine-3-carboxylates with arylalkyl-amines in boiling xylene proceeds with good yield and purity to the corresponding N-(arylalkyl)-amides. However, the presence of water in the reaction mixture has been shown to cause the formation of specific impurities: N-(arylalkyl)-1-R-2,2-dioxo-1H-2λ(6),1-benzothiazin-4-amines. According to the results of the pharmacological studies, powerful analgesics have been found among the substances synthesized.