Pyrazole → 3-Ethyl 5-methyl 2-(trifluoromethyl)-6-(difluoromethyl)-4-(1-pyrazolyl)-3,5-pyridinedicarboxylate

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Reaction Steps

To a solution of 0.94 g (0.014 mol) of pyrazole in 25 ml of anhydrous tetrahydrofuran was added 0.9 g (0.014 mol) of n-butyllithium. This cloudy solution was then transferred to a solution of 5 g (0.014 mol) of product of Example 103 in 25 ml of anhydrous THF. The solution turned red upon addition of the pyrazole lithium salt. After 45 minutes at room temperature the reaction was complete. The mixture was poured into 100 ml of water and extracted with two 75 ml portions of ether. The combined ether layers were washed with two 100 ml portions of water, dried (CaSO4), filtered and concentrated to 4.1 g of oil which was about 80% product. Trituration with petroleum ether gave 2.4 g (45%) of pure product; mp 42°-52° C. Recrystallization from cyclohexane afforded an analytical sample; mp 48.5°-50° C.

Provenance & Evidence