7-Amino-4-methylcoumarin → 2-methyl-3,4-dihydro-4-oxo-N-(2-oxo-4-methyl-2H-1-benzopyran-7-yl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide

Participants

Reaction Conditions

Reaction Steps

8.1 g of 2-methyl-3,4-dihydro-4-oxo-2H-1,2-benzothiazine-3-carboxylic acid methyl ester 1,1-dioxide and 5.7 g of 4-methyl-7-amino-coumarin are dissolved in 280 ml of xylene and the solution is heated for 21/2 hours in a bath of 170° C. to distill off the methanol formed during the reaction. The reaction mixture is refluxed for a further 5 hours, cooled, and the precipitate is collected by filtration. The precipitate is digested with 100 ml of 2N-hydrochloric acid at elevated temperature, treated with 100 ml of chloroform and extracted. The residue is collected by suction, washed successively with water, ethanol, methylene chloride and diethyl ether, washed, and dried, affording 2-methyl-3,4-dihydro-4-oxo-N-(2-oxo-4-methyl-2H-1-benzopyran-7-yl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide with a melting point above 285° C.

Provenance & Evidence