Heptanoic acid, 7-oxo-, ethyl ester → Ethyl 7-(2-phenyl-3-p-tolyl-7,8-dihydropyrido[2,3-b]pyrazin-5(6H)-yl)heptanoate

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Reaction Steps

A solution of 2-phenyl-3-p-tolyl-5,6,7,8-tetrahydropyrido[2,3-b]pyrazine (Intermediate FA) (1.03 g, 3.42 mmol) in 1,2-dichloroethane (15 ml) was treated with ethyl 7-oxoheptanoate (1.776 g, 10.25 mmol) followed by sodium triacetoxyborohydride (3.62 g, 17.09 mmol). The reaction mixture was stirred at room temperature overnight. The mixture was diluted with saturated NaHCO3 (70 ml) and was extracted with DCM (×3). The combined organics were dried (MgSO4), filtered and concentrated in vacuo. The resulting crude product was purified by chromatography on silica eluting with 0-60% EtOAc/iso-hexane to give an oil. The product was loaded onto an Isolute™ SCX-2 cartridge, washed with MeOH and eluted with 2M NH3 in MeOH. The methanolic ammonia fractions were concentrated in vacuo to afford the title compound;

Provenance & Evidence