Methylamine → (3R*,4R*)-3-({Isopropyl-[4-methoxy-3-(3-methoxy-propoxy)-benzoyl]-amino}-methyl)-4-methylaminomethyl-pyrrolidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a solution of (3S*,4R*)-3-formyl-4-({isopropyl-[4-methoxy-3-(3-methoxy-propoxy)-benzoyl]-amino}-methyl)-pyrrolidine-1-carboxylic acid tert-butyl ester (150 mg, 0.304 mmol) and magnesium sulfate (92 mg, 0.373 mmol) in THF (4 mL), methylamine (1.52 mL, 3.044 mmol, 2M in THF) is added. The solution is stirred at RT overnight under nitrogen atmosphere and NaBH4 (23 mg, 0.608 mmol) is added. The resulting mixture is stirred for 1 h and the excess reducing agent quenched with water, CH2Cl2 is added and the reaction mixture is poured into an aqueous saturated solution of NaHCO3. The organic layer is separated and the aqueous phase extracted twice with CH2Cl2, dried over Na2SO4, filtered, and concentrated in vacuo. The crude material is purified by flash chromatography on silica gel (eluent: CH2Cl2/MeOH 100:0 to 95:5+1% NH4OH ) to give the title product. TLC, Rf (CH2Cl2/MeOH 95:5)=0.05. MS (LC-MS) [M−H]+=508.1. tR (HPLC, Nucleosil C18 column, 10-100% CH3CN/H2O/5 min, 100% CH3CN/3 min, CH3CN and H2O containing 0.1% TFA, flow: 1.5 ml/min): 4.53 min.

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