[OH-].[K+].[N:3]1[CH:8]=[CH:7][CH:6]=[C:5]([CH:9]=[O:10])[CH:4]=1.[N+:11]([CH2:13][C:14]([N:16]1[CH2:20][CH2:19][CH2:18][CH2:17]1)=[O:15])#[C-:12]>CO>[N:3]1[CH:8]=[CH:7][CH:6]=[C:5]([C@@H:9]2[O:10][CH:12]=[N:11][C@H:13]2[C:14]([N:16]2[CH2:20][CH2:19][CH2:18][CH2:17]2)=[O:15])[CH:4]=1To a stirred and cooled (0° C.) solution of potassium hydroxide (0.55 g, 9.80 mmol) in methanol (10 mL) were added a mixture of 3-pyridine carboxaldehyde (1.03 mL, 10.84 mmol) and 2-isocyano-1-(pyrrolidin-1-yl)ethanone BLE 04098 (1.50 g, 10.86 mmol). The solution was stirred 3 h at 0° C. and then concentrated. The residue was partitioned between ethyl acetate (100 mL) and water. The organic layer was combined with two additional ethyl acetate extracts (2×100 mL), washed with aqueous sodium chloride and dried over MgSO4, filtered and evaporated. Concentration afforded a crude product which was purified by column chromatography on silica (CH2Cl2:MeOH=98:2) to yield to trans-(4,5-dihydro-5-(pyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanone BLE 04110B (0.95 g, 39%) as a pale yellow pale solid.
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