Tributylamine → (S)-4-Benzyloxy-2-[[2-(3,4-dichloro-phenylamino)-propyl]-(3,3-dimethoxy-propionyl)-amino]-butyric Acid methyl ester

Participants

Reaction Steps

A solution of 1.26 g (2.96 mmol) of (S)-4-benzyloxy-2-[2-(3,4-dichloro-phenylamino)-propylamino]-butyric acid methyl ester in 30 ml CH2Cl2 was treated with a solution of 0.91 g (3.55 mmol) of 2-chloro-1-methylpyridinium iodide and 0.48 g (3.55 mmol) of 3,3-dimethoxy-propionic acid (synthesized from methyl 3,3-dimethoxy-propionate by hydrolysis with LiOH) in 20 ml of CH2Cl2. The suspension was cooled and treated at 0° C. with 1.77 ml (7.41 mmol) of tributylamine. The cooling bath was removed after 10 min and stirring was continued 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 1.53 g (96%) of the title compound as a 71:29 mixture of the (R) and (S) diastereomers. Yellow oil, MS: 541.2 (MH+, 2Cl).

Provenance & Evidence