[C:1]1([C:7]2[CH:8]=[CH:9][C:10]([C:19]([O:21]CC)=O)=[N:11][C:12]=2[C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[CH3:24]NCCNC.C[Al](C)C>C1(C)C=CC=CC=1>[C:1]1([C:7]2[CH:8]=[CH:9][C:10]([C:19](=[O:21])[CH3:24])=[N:11][C:12]=2[C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1General Procedure O. To a solution of ethyl 5,6-diphenylpyridine-2-carboxylate (Compound 21, 246 mg, 0.81 mmol) in toluene (5 ml) was added N,N′-dimethylethylenediamine (DMEDA, 78.7 mg, 0.89 mmol) and trimethylaluminum (1.2 ml, 2.44 mmol, 2 M in toluene) dropwise under argon at room temperature. After the mixture was refluxed at 112° C. for 2.5 hours, it was quenched with water, and the products were extracted with ethyl acetate. The combined organic layers were washed with brine, and dried over Na2SO4. The filtered solvents were concentrated in vacuo, and the residue was purified by silica gel chromatography (15% ethyl acetate in hexane) to give title compound as a yellow solid.
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