Tetrahydrofuran → Diethyl [6-(1,4-dioxaspiro[4.5]dec-8-yloxy)-2-(trifluoromethyl)pyrimidin-4-yl]malonate

Participants

Reaction Conditions

Reaction Steps

To a mixture of tetrahydrofuran (40 mL) and NaH in mineral oil (1.1 g, 28 mmol) at 0° C. was added ethyl malonate (4.2 mL, 28 mmol), dropwise. 4-chloro-6-(1,4-dioxaspiro[4.5]dec-8-yloxy)-2-(trifluoromethyl)pyrimidine (described in Example 1, Step 1) (3.75 g, 11.1 mmol), was then added. The reaction mixture was stirred at 64° C. After 3 hours, HPLC & LCMS analysis showed 70% reaction completion. Heated for another 6 hours, and then cooled to 20° C. Only a trace of decarboxylation product formed. The reaction was diluted with aqueous bicarbonate, and extracted with EtOAc. The EtOAc extract was washed with brine, dried over Na2SO4, and evaporated in vacuo to give 8.5 g oil (includes excess ethyl malonate and mineral oil). The crude product was purified by chromatography on a 120 g silica gel column, using solvent A=hexane; solvent B=EtOAc; flow 60 mL/min; A, 3 min; Gradient to 40% B in 40 min; detector set at 254 nm; collected 47 mL fractions; retention time, 28 min. The combined fractions were evaporated to give 4.6 g, colorless oil, 90% yield. 1H NMR (300 MHz, CDCl3): δ7.05 (s, 1H); 5.30 (m, 1H, OCH); 4.85 (s, 1H, CH); 4.25 (m, 2H, OCH2); 3.95 (s, 4H, OCH2); 1.6-2.1 (m, 8H); 1.28 (t, 3H, CH3).

Provenance & Evidence