N1CCC[C@H]1C(O)=O.[N:9]1([C:14]2[CH:21]=[CH:20][C:17]([CH:18]=O)=[CH:16][CH:15]=2)[CH:13]=[N:12][CH:11]=[N:10]1.[CH3:22][C:23]1([CH3:31])[O:28][C:27](=[O:29])[CH2:26][C:25](=[O:30])[O:24]1.CC1NC(C)=C(C(OCC)=O)CC=1C(OCC)=O>C(O)C.C(O)(C)C>[N:9]1([C:14]2[CH:21]=[CH:20][C:17]([CH2:18][CH:26]3[C:27](=[O:29])[O:28][C:23]([CH3:31])([CH3:22])[O:24][C:25]3=[O:30])=[CH:16][CH:15]=2)[CH:13]=[N:12][CH:11]=[N:10]1L-Proline (1.81 g, 15.6 mmol) was added to a stirring, heterogeneous mixture of 4-(1H-1,2,4-triazol-1-yl)benzaldehyde (13.5 g, 78.0 mmol, Intermediate 45, step a) and 2,2-dimethyl-1,3-dioxane-4,6-dione (11.2 g, 78.0 mmol) in ethanol (520 mL) at 23° C. After 1.5 hours, diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate (19.7 g, 78.0 mmol) was added in one portion. After 16 hours, the ethanol was removed by rotary evaporation at 35° C. to afford a yellow solid. Isopropanol (300 mL) was added and the heterogeneous mixture was stirred for 10 minutes at 23° C. The mixture was filtered and the filter cake was washed with isopropanol (150 mL). The solids were collected and dried under vacuum to provide the titled compound as a white solid.
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