Lithium Hydroxide → 17-Ethoxymethoxy-13-methyl-2,14-dioxo-3,13-diaza-tricyclo[13.3.0.0*4,6*]-octadec-7-ene-4-carboxylic acid

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Reaction Steps

A solution of the ester (115) (1.48 g, 3.39 mmol) in 1:1:1 THF-methanol-aq. 1M LiOH (102 ml) was stirred at 60° C., then at room temperature overnight. The reaction mixture was then concentrated into approximately ⅓ of the volume, diluted with water (30 ml) and acidified to approx. pH 4 using aq. 10% citric acid (60 ml), then washed with ethyl acetate (3×50 ml). The combined organic layers were washed with brine (1×100 ml), then dried (Na2SO4), filtered and concentrated. Column chromatography of the residue using 9:1 ethyl acetate-methanol as eluent gave the title compound as a slight yellow (The coloring from the previous step was removed during work up and chromatography). Yield: 1.35 g, 97%. LR-MS: Calcd for C21H31N2O6: 407. Found: 407 [M−H].

Provenance & Evidence