Trifluoroacetic acid → HCID 25160352, compound

Participants

Reaction Steps

A stirred solution of (R)-3-(tert-butyldimethylsilyloxy)-N-(tert-butoxycarbonyl)pyrrolidine (1.00 g, 3.32 mmol) and dirhodium(II) tetrakis[(S)—N-[p-(dodecylphenyl)sulfonyl]prolinate] {Rh2(R-DOSP)4} (125 mg, 0.07 mmol) in 2,2-dimethylbutane was stirred under reflux. Diazo-(3,4-dichlorophenyl)acetic acid methyl ester (1.63 g, 6.64 mmol) in a 1:4 mixture of trifluorotolune: 2,2-diethylbutane was added via syringe pump over a 3 hour period. The mixture was stirred under reflux for an additional 2 hours and then stirred at room temperature overnight. The mixture was then concentrated, diluted with dichloromethane (100 mL) and charged with trifluoroacetic acid (1.97 mL, 26.6 mmol). After 16 hours, the solution was concentrated, the residue dissolved in Et2O (100 mL), and extracted with 10% HCl (3×100 mL). The aqueous layers were basified with solid NaHCO3 (solid) and 1M NaOH to pH=8−9. The aqueous phase was then back extracted ethyl acetate (3×50 mL) and the organic phases were washed with brine (25 mL), dried with Na2SO4, and filtered. The extraction was reduced and purified by chromatography to afford the titled compound as a clear oil: 391 mg (35% yield). 1H NMR (500 MHz, CDCl3) δ 7.50 (s, 1H), 7.41-7.39 (d, J=8 Hz, 1H), 7.24-7.22 (m, 1H), 4.41 (m, 1H), 3.99 (m, 1H), 3.67 (s, 1H), 3.42 (d, J=9 Hz, 1H), 3.04 (dd, J=4.5, 7.5 Hz, 1H), 2.83 (m, 1H), 2.00 (m, 4H), 1.66 (m, 1H). 13C NMR (75 MHz, CDCl3) δ 172.3 (C), 137.4 (C), 132.7 (C), 131.8 (C), 130.6 (CH), 130.5 (CH), 128.1 (CH), 72.3 (CH), 59.3 (CH2), 56.6 (CH), 54.8 (CH), 52.2 (CH3), 40.2 (CH2); IR (neat): 1753 cm−1; HRMS (ESI) m/z Calc'd for [C13H15Cl2NO3]+ (M+): 303.0429. Found: 303.0437.

Provenance & Evidence