2(1H)-Pyrimidinone, tetrahydro-1,3-dimethyl- → ethyl (2E,4E,6E)-6-fluoro-7-(4-isopropyl-7-methoxy-2,2-dimethyl-2H-chromen-6-yl)-3-methyl-octa-2,4,6-trienoate

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Reaction Conditions

Reaction Steps

To a solution of ethyl 4-(diethoxyphosphoryl)-3-methyl-but-2E-enoate (240 mg, 0.91 mmol) in THF (10 mL), and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU, 0.13 mL) under argon at −78° C. was slowly added n-butyl lithium (1.6 M in hexanes, 0.60 mL, 0.96 mmol). The resulting mixture was stirred at −78° C. for 15 min before a solution of (2E)-2-fluoro-3-(4-isopropyl-7-methoxy-2,2-dimethyl-2H-chromen-6-yl)-but-2-enal (Compound 95, 100 mg, 0.31 mmol) and THF (3 mL) was added via cannula. The resulting mixture was stirred at 0° C. for 1 h. The reaction was quenched with saturated NH4Cl, and the product was extracted with diethyl ether. The combined ethereal layers were washed with water and brine, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by flash column chromatography (silica gel, 5% ethyl acetate in hexane) to yield the title compound as a yellow oil.

Provenance & Evidence