反应详情

温度

-78 °C

A solution of 5-bromo-2-fluoropyridine (2 g, 0.011 mol) in 50 mL of dry ether under nitrogen was cooled to −78° C. n-butyllithium (7.5 mL, 0.011 mol, 1.6 M solution in hexane) and TMEDA (2.5 g, 0.022 mol) were added dropwise. The orange solution was stirred for an additional 1 h at −78° C. and then treated dropwise over 10 min with a solution of 1,4-cyclohexanedione monoethylene ketal (1.8 g, 0.011 mol) in 20 mL of dry THF. The reaction mixture was stirred for 1 h, allowed to warm to 20° C. and poured into ice water (400 mL). The organic layer was separated, and the aqueous layer was extracted twice with EtOAc (20 mL×2). The combined organic extracts were dried over MgSO4 and evaporated to give 2 g of white solid. Chromatography on silica gel afforded 1.7 g (67% yield) of white crystals: MS: 254 (M+1)+.

1. additionwere added dropwise
2. stirringThe reaction mixture was stirred for 1 h
3. temperatureto warm to 20° C.
4. customThe organic layer was separated
5. extractionthe aqueous layer was extracted twice with EtOAc (20 mL×2)
6. dry with materialThe combined organic extracts were dried over MgSO4
7. customevaporated