Alkylation of 1,3-benzothiazin-4-one 2-oxo-, 2-arylimino-, and 2-thioxo derivatives

Abstract

Sodium salt of 3Н -benzo[e][1,3]thiazine-2,4-dione is easily alkylated at position 3. In the case of 2-(arylimino)-2,3-dihydrobenzo[e][1,3]-thiazin-4-ones, the alkylation reaction at this position occurs regioselectively. Alkylation of 2-thioxo-2,3-dihydrobenzo[e][1,3]thiazin-4-one under the same conditions produced regioisomers, but S-alkylation at the exocyclic sulfur atom occurred in the presence of triethylamine. The reaction of 1-(4-oxo-3,4-dihydrobenzo[e][1,3]thiazin-2-ylidene)guanidine with methyl anthranilate led to the formation of tetracyclic quinazolinо[2,1-b]quinazolinedione.