p-Toluenesulfonic acid → 7-[(1-Ethoxyethoxy)methyl]-7,8-dihydro-5H-[1,4]oxazino[4,3-b]thieno[3,2-e]-1,2-thiazine-5-one 10,10-dioxide

Participants

Reaction Steps

A suspension of the product from Step C (10 g, 34.84 mmol) in anhydrous THF (200 mL) at 0° C. was combined with ethyl vinyl ether (5.02 g, 69.68 mmol) and p-toluenesulfonic acid (1.32 g, 6.9 mmol); this mixture was stirred until it became homogeneous. The reaction mixture was filtered through silica and the solvent evaporated to give a residue which was purified by column chromatography (silica, ethyl acetate/hexane, 3:7) to give 6.8 g (54%) of an oil.

Provenance & Evidence