Isopropylamine → (3S*,4R*)-4-(Isopropylamino-methyl)-pyrrolidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester

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Reaction Steps

A solution of (3S*,4S*)-4-formyl-pyrrolidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester (2.87 g, 10.56 mmol) and isopropylamine (2.72 mL, 31.68 mmol) in 1,2-dichloroethane (150 mL) is stirred 25 min, before addition of NaBH(OAc)3 (3.12 g, 14.78 mmol) follows. The solution is stirred for 4 h, then diluted with CH2Cl2 and washed with an aqueous saturated solution of NaHCO3. The combined organic extracts are dried over Na2SO4 and concentrated. The crude material is purified by flash chromatography on silica gel (eluent: CH2Cl2/MeOH 100:0 to 80:20) to give the title product. TLC, Rf (CH2Cl2/MeOH 95:5)=0.1.

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