Diisopropylethylamine → (+/-)-1-(5-Chloro-2-ethoxycarbonylmethoxy-phenyl)-3,4-dihydro-1H-isoquinoline-2-carboxylic acid 2-bromo-benzyl ester

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Reaction Steps

To a solution of (±)-[4-chloro-2-(1,2,3,4-tetrahydro-isoquinolin-1-yl)-phenoxy]-acetic acid ethyl ester hydrochloride (836 mg, 2.00 mmol, 1.0 eq.) and DIPEA (0.86 mL, 5.00 mmol, 2.5 eq.) in DCM (30 mL), carbonic acid 2-bromo-benzyl ester 2,5-dioxo-pyrrolidin-1-yl ester (787 mg, 2.40 mmol, 1.2 eq.) was added. The mixture was stirred at r.t. during 2 hours. The reaction was quenched with 1M aq. citric acid soln. (30 mL). The layers were separated. The aq. phase was extracted with DCM (3×). The comb. org. phases were dried over MgSO4, filtered, and concentrated in vacuo. To a solution of the previous mixture in EtOH (1.1 mL), conc. H2SO4 (0.10 mL) was added. The solution was stirred at r.t. during 3 hours. Water and 5% aq. NaOH soln. were added and the mixture was extracted with DCM (3×). The comb. org. phases were dried over MgSO4, filtered and concentrated in vacuo to give the desired product as a pale yellow oil.

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