p-Toluenesulfonic acid → Methyl (4E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoate

Participants

Reaction Steps

A solution of 15.1 g (47.1 mmol) of (E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxoisobenzofuran-5-yl)-4-methyl-4-hexenoic acid (mycophenolic acid) and 0.7 g (3.7 mmol) of p-toluenesulfonic acid in 400 ml of methanol was allowed to stand at room temperature for 3 days. The mixture was concentrated under reduced pressure to approximately 75 ml and then partitioned between aqueous sodium bicarbonate and ethyl acetate. The organic phase was further washed with brine and then dried over sodium sulfate. Concentration of the organic phase under reduced pressure gave 15.4 g (46.0 mmol, 98%) of methyl (E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7- methyl-3-oxoisobenzofuran-5-yl)-4-methyl-4-hexenoate as a white solid, mp 104°-105° C.

Provenance & Evidence