Triethylamine → (3S*,4R*)-4-({Isopropyl-[4-methoxy-3-(3-methoxy-propoxy)-benzoyl]-amino}-methyl)-pyrrolidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester

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Reaction Steps

A mixture of (3S*,4R*)-4-(isopropylamino-methyl)-pyrrolidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester (2.58 g, 8.2 mmol), 3-(3-methoxy-propoxy)-4-methoxy-benzoic acid (1.93 g, 8.04 mmol), bis(2-oxo-3-oxazolidinyl)phosphinic chloride (2.3 g, 9.02 mmol) and triethylamine (4.57 μL, 32.81 mmol) in CH2Cl2 (50 mL) is refluxed for 2 h and then quenched by the addition of aqueous NaHCO3 solution. The organic layer is separated, and the aqueous phase is extracted 3 times with AcOEt. The combined organic extracts are dried (Na2SO4), and the solvent is removed in vacuo. The crude product is purified by flash chromatography on silica gel (eluent: c-hexane/AcOEt 50:50 to 0:100 and then AcOEt/MeOH 95:5) to give the title product. TLC, Rf (CH2Cl2/MeOH 95:5)=0.3. tR (HPLC, C18 column, 10-100% CH3CN/H2O/5 min, 100% CH3CN/3 min, CH3CN and H2O containing 0.1% TFA, flow: 1.5 mL/min): 5.76 min.

Provenance & Evidence