Water → HCID 9948928, compound

Participants

Reaction Steps

9.0 g (5.5 mmol) of methyl (B)-6-(4-carboxy-1,3-dihydro-6-methoxy-7methyl-3-oxoisobenzofuran-5-yl)-4-methyl -4-hexenoate, a compound of Formula 5, was converted to crude methyl E-6-(1,3-dihydro-4-isocyanato-6-methoxy-7-methyl-3-oxoisobenzofuran-5-yl)-4-methyl-4-hexenoate, a compound of Formula 6, as described in Preparation 6 above without purification. The resulting 4-isocyanate was redissolved in 50 ml of 1,4-dioxane and treated with 16 ml of water and 2.0 g (47.7 mmol) of lithium hydroxide monohydrate. The mixture was stirred at room temperature for 2 hours and then partitioned between aqueous 1N sodium hydrogen sulfate and ethyl acetate. The organic phase was washed twice with water, once with brine, and was dried over magnesium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by chromatography on silica gel, using 50:40:1 hexane:ethyl acetate:acetic acid as eluant to give 1.28 g (4.0 mmol) of (E)-6-(4-amino-1,3-dihydro-6-methoxy-7-methyl-3-oxoisobenzofuran-5-yl)-4-methyl-4-hexenoic acid as a white solid, mp 130°-131° C.

Provenance & Evidence