Water → HCID 18605769, compound

Participants

Reaction Steps

To a suspension of Boc-cyclopropyl leucine p-nitrobenzyl ester (8) (300 mg, 7.9 mmol) in MeOH (20 ml) was added 2N NaOH soln. (7 ml) under ice cooling and the mixture was stirred for 3 hr at room temperature, the starting material gradually dissolved and the mixture turned yellow. Water (10 ml) was added and the MeOH was evaporated in vacuo. The aqueous residue was washed with AcOEt, cooled in an ice bath and acidified by the addition of 10% citric acid to pH 3. The resulting white precipitate was extracted with AcOEt (3×20 ml) and the extract was washed with sat. NaCl soln, dried over Na2SO4, and evaporated in vacuo. The resulting of Boc-cyclopropyl-leucine (9) was recrystallized from AcOEt-n-hexane to give 140 mg, (72.5%) as colorless prisms; mp 196°-197° C. (dec.); IR: (KBr) 3230(NH), 1690(C=O), 1645(C=O). NMR (CDCl3 +DMSOd6) δ:5.78 (s, 1H, NH), 1.2-1.8 (m,4H,CH2, CHx2),1.4 (s,9H,Boc), 0.9-1.1 (m,6H,(CH3)2CH).

Provenance & Evidence