Sodium Hydroxide → N-Boc-cis-4-hydroxy-L-proline methyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 1 N aqueous sodium hydroxide (6 mL) was added to a cold (0†° C.) stirred solution of N-tert-butoxycarbonyl-cis-4-formyloxy-L-proline methyl ester (I, 4.07 g) in tetrahydrofuran (6 mL). After stirring at 0° C. for 3 hr, a solution of 1 N aqueous sodium hydroxide (3 mL) was added and additionally stirred at 0° C. for 30 min. The mixture was evaporated in vacuo. The residue was diluted with ethyl acetate and washed with brine. The organic layer was dried over anhydrous sodium sulfate and evaporated in vacuo. The residue was purified by silica gel column chromatography (ethyl acetate:chloroform=1:5 to 1:1, v/v) to give the title compound (2.77 g) as a colorless oil: 1H NMR (400 MHz, CDCl3) δ 1.35-1.54 (m, 9H), 1.78 (br s, 1H), 2.00-2.15 (m, 1H), 2.27-2.39 (m, 1H), 3.50-3.59 (m, 1H), 3.61-3.71 (m, 1H), 3.63-3.77 (m, 1H), 3.78-3.80 (m, 3H), 4.29 (dd, J=1.5, 9.8 Hz, 1H), and 4.33-4.39 (m, 1H).

Provenance & Evidence