O-Xylene → 4-Hydroxy-2-methyl-N-(2-pyridyl)-2H-[1]benzothieno[2,3-e]-1,2-thiazine-3-carboxamide-1,1-dioxide

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Reaction Steps

5 g. of 3-carbomethoxy-4-hydroxy-2-methyl-2H-[1]benzothieno[2,3-e]-1,2-thiazine 1,1-dioxide and 3 g. of 2-aminopyridine are treated with 150 ml. of a xylene isomer mixture and heated so that the resulting methanol distils off azeotropically. After 6 hours, the mixture is left to cool to room temperature. The cyrstals obtained are filtered off under suction and washed with a xylene mixture. After recrystallization from dimethylformamide and addition of methanol, there is obtained 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-[1]benzothieno[2,3-e]-1,2-thiazine-3-carboxamide 1,1-dioxide in the form of yellow crystals of melting point 222°-224° C.

Provenance & Evidence