Water → cis-N-Boc-4-(4-bromobenzyl thio)-L-proline

To a solution of Na (0.25 g) (0.011 mol) in 3 mL of MeOH was added 4-bromobenzyl mercaptan (2.2 g) (0.011 mol). The reaction mixture was stirred for 1 h. Trans-N-Boc-4-methanesulfonyloxy-L-proline methyl ester (1.2 g) (0.0037 mol) (Preparation 9) was added and the mixture refluxed for 18 hrs. Upon cooling to RT, 40 mL of water was added and the mixture was extracted with EtOAc. The aqueous layer was acidified with 1 N HCl and extracted with DCM. The combined organic extracts were washed with water, dried over MgSO4, and the solvent evaporated in vacuo to afford cis-N-Boc-4-(4-bromobenzyl thio)-L-proline (1.08 g). NMR (CDCl3, 200 MHz): 10.65 (1H, COOH), 7.4 (2H, d), 7.15 (2H, d), 4.15-4.35 (1H, m), 3.65 (2H, s), 2.95-3.35 (2H, m), 2.4-2.6 (1H, m), 1.85-2.2 (1H, m), 1.3-1.5 (9H). To a solution of cis-N-Boc-4-(4-bromobenzyl thio)-L-proline (1.08 g) in 10 mL of MeOH was added dropwise SOCl2 (0.2 mL), and the mixture was stirred for 72 hrs at RT. The solvent was evaporated under reduced pressure and the residue dissolved in DCM. The organic layer was washed with dilute aqueous NaHCO3, water, and dried over MgSO4. The solvent was evaporated in vacuo to afford cis-4-(4-bromo-benzylthio)-L-proline methyl ester (0.6 g).

1. temperaturethe mixture refluxed for 18 hrs
2. extractionthe mixture was extracted with EtOAc
3. extractionextracted with DCM
4. washThe combined organic extracts were washed with water
5. dry with materialdried over MgSO4
6. customthe solvent evaporated in vacuo

ORD record

ord-5b2f226166e4404099c551c600fa9b34

Source dataset

uspto-grants-2004_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06710064B2