Tributylamine → 4-[[(R)-2-(3-Chloro-4-trifluoromethyl-phenylamino)-propyl]-(3,3-dimethoxy-propionyl)-amino]-butyric acid tert-butyl ester

Participants

Reaction Steps

A solution of 1.25 g (3.20 mmol) of 4-[(R)-2-(3-chloro-4-trifluoromethyl-phenylamino)-propylamino]-butyric acid tert-butyl ester (22% ee) in 25 ml CH2Cl2 was treated with a solution of 1.00 g (3.80 mmol) of 2-chloro-1-methylpyridinium iodide and 0.51 g (3.80 mmol) of 3,3-dimethoxy-propionic acid (synthesized from methyl 3,3-dimethoxy-propionate by hydrolysis with LiOH) in 5 ml of CH2Cl2. The suspension was cooled and treated at 0° C. with 1.89 ml (7.90 mmol) of tributylamine. The reaction was naturally warmed to RT over night. The reaction was extracted with 10% aq. KHSO4 solution/diethyl ether (3×). The organic phases were washed with 10% aq. KHSO4 solution (2×), sat. aq. NaHCO3 solution, 10% aq. NaCl solution and dried over Na2SO4 to yield 1.68 g (quantitative) of the title compound as a 61:39 mixture of the (R) and (S) diastereomers as light brown oil. MS: 511.22 (MH+, Cl).

Provenance & Evidence