1-Hydroxybenzotriazole → Rac.-n-[2-chloro-4-[1-hydroxy-3-(3-hydroxyphenyl)prop-2-en-1-yl]benzoyl]-2-(dimethoxyphosphinyl)glycine methyl ester

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Reaction Steps

Diisopropylethylamine (0.48 mL, 2.8 mmol) was added to a solution of rac.-2-chloro-4-[1-hydroxy-3-(3-hydroxyphenyl)prop-2-en-1-yl]benzoic acid (Example 93; 225 mg, 0.69 mmol), rac.-2-(dimethoxyphosphinyl)glycine methyl ester (Example 125) freshly prepared from rac.-N-(benzyloxycarbonyl)-2-(dimethoxyphosphinyl)glycine methyl ester (331 mg, 1 mmol), O-(benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (284 mg, 0.75 mmol) and 1-hydroxybenzotriazole (102 mg, 0.76 mmol) in N,N-dimethylformamide (5 mL). The solution was stirred at room temperature for 17 h and then it was concentrated under high vacuum to remove N,N-dimethylformamide. Ethyl acetate (25 mL) was added and the resulting solution was washed in turn with 0.5N hydrochloric acid solution (10 mL), brine (10 mL), saturated sodium bicarbonate solution (10 mL) and brine (10 mL). Each of the aqueous layers was back-extracted in turn with ethyl acetate (10 mL). The combined organic layers were dried (MgSO4), filtered, evaporated and chromatographed over silica gel (50-100% ethyl acetate/hexanes, then 5% methanol/ethyl acetate) to furnish rac.-N-[2-chloro-4-[1-hydroxy-3-(3-hydroxyphenyl)prop-2-en-1-yl]benzoyl]-2-(dimethoxyphosphinyl)glycine methyl ester (240 mg, 72% yield) as an oil.

Provenance & Evidence