Dimethyl Sulfoxide → 2-(R)-(3-(R)-Formyl-4-(S)-phenylpyrrolidin-1-yl)-3-(cyclobutyl)propionic acid, benzyl ester

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Reaction Conditions

Reaction Steps

A solution of 1.29 mL (14.8 mmol) of oxalyl chloride in 15 mL of CH2Cl2 at −78° C. was treated with 2.10 mL (29.7 mmol) of DMSO maintaining the temperature at less than −60° C. The resulting mixture was stirred cold for 5 min. A solution of 2.33 g (5.9 mmol) of 2-(R)-(3-(R)-(hydroxymethyl)-4-(S)-phenylpyrrolidin-1-yl)-3-(cyclobutyl)propionic acid, benzyl ester (from Step B) in 10 mL of CH2Cl2 was added maintaining the temperature at less than −60° C. The resulting mixture was stirred cold for 30 min. The mixture was treated with 10.3 mL (59.3 mmol) of DIEA maintaining the temperature at less than −60° C. The reaction was warmed to 0° C., stirred for 20 min and quenched with H2O . The mixture was partitioned between 250 mL of CH2Cl2 and 100 mL of H2O and the layers were separated. The aqueous layer was extracted with 250 mL of CH2Cl2. The combined organic phases were dried over Na2SO4 and concentrated. Flash chromatography on 100 g of silica gel using 4:1 v/v hexanes/ether as the eluant afforded 2.30 g (97%) of the title compound: 1H NMR (300 MHz) δ1.54-2.08 (m, 8H), 2.31 (m, 1H), 2.75 (t, J=8.6 Hz, 1H), 2.96 (m, 1H), 3.11-3.35 (m, 4H), 3.56 (q, J=7.9 Hz, 1H), 5.16 (s, 2H), 7.19-7.39 (m, 10H), 9.63 (d, J=2.2 Hz, 1H).

Provenance & Evidence