Imidazole → cis4-(tert-butyldimethylsilyloxy)-N-benzyloxycarbonyl-D-proline

Participants

Reaction Steps

To a mixture of cis4-hydroxy-N-benzyloxycarbonyl-D-proline (18.74 g) and imidazole (11.56 g) in DMF (100 mL) was added TBDMSCl (23.36 g) at 5° C. After stirring at room temperature for 16 hours, the reaction mixture was diluted with EtOAc-hexane (1:1, 600 mL), washed with 1N HCl, water and brine, dried (MgSO4), and evaporated in vacuo. The residue was dissolved in MeOH-THF (3:1, 400 mL). To the solution was added an aqueous solution (100 mL) of K2CO3 (9.77 g) at 5° C., and the mixture was stirred at the same temperature for 1 hour. The organic solvent was evaporated, and the residue was adjusted to pH 2 by the addition of 3N HCl, and extracted with EtOAc. The organic layer was washed with water and brine, dried (MgSO4), and evaporated in vacuo. The residue was purified by silica gal column chromatography to give cis-4-(tert-butyldimethylsilyloxy)-N-benzyloxycarbonyl-D-proline (23.99 g).

Provenance & Evidence