反应详情

To a −78° C. solution of diisopropylamine (0.3 mL, 2.1 eq) in diethyl ether (3 mL) was added a 2.5 M solution of n-butyllithium in hexanes (Aldrich) (0.84 mL, 2.1 eq). The resulting mixture was stirred for 15 minutes. To this mixture was added a solution of (2,4-difluorophenoxy)acetic acid methyl ester (425 mg, 2.1 eq) in diethyl ether (2 mL) via a syringe, and the resulting mixture was stirred at −78° C. for 30 minutes, after which a solution of 4-nitro-2-(2-trimethylsilanyl-ethoxymethyl)-2H-pyrazole-3-carbaldehyde (271 mg, 1 mmol) in diethyl ether (2 mL) was added. The resulting mixture was stirred for 2 hours. The −78° C. reaction mixture was diluted with a saturated aqueous ammonium chloride solution, then diluted with ethyl acetate (150 mL) and water (25 mL). The organic layer was separated, washed with brine (1×50 mL), dried over magnesium sulfate, filtered and concentrated to give the crude product as an oil (709 mg). Purification of the crude product by Preparative Thin Layer Chromatography eluting with 25% ethyl acetate in hexanes gave the title compound as a diastereomeric mixture (257 mg, thick colorless oil). M+=473.

1. stirringthe resulting mixture was stirred at −78° C. for 30 minutes
2. stirringThe resulting mixture was stirred for 2 hours
3. customThe −78° C. reaction mixture
4. customThe organic layer was separated
5. washwashed with brine (1×50 mL)
6. dry with materialdried over magnesium sulfate
7. filtrationfiltered
8. concentrationconcentrated
9. customto give the crude product as an oil (709 mg)
10. customPurification of the crude product by Preparative Thin Layer Chromatography
11. washeluting with 25% ethyl acetate in hexanes