Hydrochloric Acid → Diethyl 2,6-bis(trifluoromethyl)-4-methoxy-3,5-pyridinedicarboxylate

Temperature

-78 °C

To a cold (-78° C.) solution of LDA, from 0.02 mol (2.8 ml) of diisopropylamine, 0.0208 mol of n-BuLi, and 30 ml of DME was added a solution of 4.65 g (0.015 mol) of product of Example 4 in 20 ml of DME. The resulting greenish solution was stirred at -78° C. for 10 minutes and treated with 2.7 ml (0.035 mol) of ethyl chloroformate. The reaction mixture was warmed to room temperature in 40 minutes, then poured into a mixture of 20 ml of concentrated HCl and 50 ml of water. The mixture was extracted with ether (200 ml). The ether extract was dried and concentrated. The residue was kugelrohr distilled at 13 Pa. The earlier fraction (pot temperature 50°-65° C.) was discarded. The later fraction (pot temperature 90° C.) was an oil (5.47 g) which was crystallized from hexane at low temperature to give 4.4 g (75%) of product; mp 46.5°-47.5° C.

1. temperatureThe reaction mixture was warmed to room temperature in 40 minutes
2. extractionThe mixture was extracted with ether (200 ml)
3. extractionThe ether extract
4. customwas dried
5. concentrationconcentrated
6. distillationThe residue was kugelrohr distilled at 13 Pa
7. customThe earlier fraction (pot temperature 50°-65° C.)
8. customThe later fraction (pot temperature 90° C.)
9. customwas crystallized from hexane at low temperature

ORD record

ord-951e4010df13437c9835041e3e7662b9

Source dataset

uspto-grants-1990_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04921530