Propionitrile → (2S,4R)-4-(4-Bromo-2-chloro-phenylsulfanyl)-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester

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Reaction Steps

CAS #1252633-25-2 (5.3 g, 12.3 mmol, Eq: 1.00) was dissolved in propionitrile (40 ml) and 4-bromo-2-chlorobenzenethiol (3.3 g, 14.8 mmol, Eq: 1.20) was added. Now triethyl amine (2.49 g, 3.43 ml, 24.6 mmol, Eq: 2.00) was added. The reaction mixture was stirred at reflux over night. The reaction mixture was poured into 100 ml 10% Na2CO3 and extracted with EtOAc (2×100 mL). The organic layer was extracted with 100 ml 0.1N HCl, dried over Na2SO4, filtered and evaporated. The crude material was purified by flash chromatography (silica gel, 120 g, 0% to 30% AcOEt in heptane in 30 min) to yield a colorless oil (4.72 g; 85%). m/z=352.1 [M+H-Boc]+.

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