To a mixture of ethyl (2E)-3-(6-{[(3R)-1-(4-aminophenyl)-3-pyrrolidinyl]amino}-3-pyridinyl)acrylate (178 mg) and 50% phosphinic acid (5 mL) was added sodium nitrite (62.7 mg) in H2O at 4° C. The reaction mixture was stirred for 2 hours at 4° C. The resulting mixture was neutralized with saturated NaHCO3 and extracted with chloroform. The organic layer was dried over MgSO4, filtered, and evaporated in vacuo. The residue was purified by column chromatography on silica gel to give ethyl (2E)-3-(6-{[(3R)-1-phenyl-3-pyrrolidinyl]amino}-3-pyridinyl)acrylate (49.0 mg).
