Citric Acid → 1-N-BOC-4-(6-Methoxy-3-methylisoquinolin-1-yloxy)pyrrolidine-2-carboxylic acid

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Reaction Steps

N-BOC-4-hydroxy-L-proline (A; 281 mg; 1.21 mmol) was dissolved in DMSO (3 mL) at RT then potassium t-butoxide (270 mg; 2.4 mmol) was added. The resulting solution was stirred at RT for 2 h then cooled to 0° C. Next a solution of isoquinoline 14 in DMSO (3 mL) was added dropwise to the cold solution of A and t-BuOK, then the mixture was allowed to warm up to RT. The solution was stirred for 16 h, and an addition 0.2 equivalents of A was added and the mixture stirred for an additional 1.5 h. The reaction mixture was acidified to pH=4 with 5% aq. citric acid. The solution was extracted with ethyl acetate and the organic phase washed with water followed by saturated aq. NaCl. The organic phase was concentrated in vacuo to give the title compound.

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