Synthesis of a Series of 2,3-Disubstituted 4H-1,4-Benzothiazines and X-ray Crystal Structure of Ethyl 7-Chloro-3-Methyl-4H-1,4-Benzothiazine-2-Carboxylate

Abstract

The reaction between 2-aminobenzenethiol and ethyl acetoacetate is studied under a variety of conditions, and a procedure for the exclusive synthesis of 1,4-benzothiazines by the neat reaction of substituted aminothiols with bketoesters and b-dicarbonyl compounds in 85-96% yield is described. With microwave heating, even when both the reactants are solid, yields are high, reaction times brief, and work-up easy. A facile reaction is also observed even in a solid-state reaction. The molecular structure of ethyl 7-chloro-3-methyl-4H-1,4-benzothiazine-2-carboxylate (4d) was determined by single-crystal X-ray diffraction.

FT-IR, FT-Raman and computational study of 1H-2,2-dimethyl-3H-phenothiazin-4[10H]-one

“…In the present case the C@O bond length is 1.237 Å (XRD), 1.2276 (DFT). Dandia et al [63] reported this bond length as 1.343 Å and Jadeja et al [65] reported this as 1.252 Å. The …”

“…Dandia et al [63] reported corresponding bond lengths for CAN as 1.364 and 1.412 Å for similar derivative and Endredi et al [64] reported these values as 1.408 Å and 1.412 Å, and Jadeja et al [65] reported this as 1.428 Å, Tamasi et al [66] reported this as 1.378 Å, 1.377 Å and 1.397 Å. In the present case the C@O bond length is 1.237 Å (XRD), 1.2276 (DFT).…”