Phosphorus sulfide (P2S5) → HCID 14234715, compound

Participants

Reaction Steps

A mixture of methyl 3,4-dihydro-2-isopropyl-3-oxo-2H1,4-benzothiazine-4-acetate (50.0 g), phosphorus pentasulfide (79.5 g), and toluene (450 ml) was refluxed for 5.5 hours with stirring. After cooling, the insoluble matter was removed by filtration, and the solvent was evaporated off. To the residue isopropyl ether (300 ml) was added, and the insoluble matter was removed by filtration. The filtrate was concentrated, and the residue was crystallized from 2-propanol, to give methyl 3,4-dihydro-2- isopropyl-3-thioxo-2H-1,4-benzothiazine-4-acetate as crystals. Yield was 27.0 g (51.0%). Recrystallization from 2-propanol gave yellow prisms. mp 99°-100° C.

Provenance & Evidence