Реакция #86696

Уравнение реакции

tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate

1-bromo-3,4-difluoro-2-(trifluoromethyl)benzene

Na2CO3

→

tert-butyl 4-(3,4-difluoro-2-(trifluoromethyl)phenyl)-5,6-dihydropyridine-1(2H)-carboxylate

Выход 92.0%

Растворители

DME

LiCl

Условия реакции

Обработка

1. 1
   ТемператураThe mixture cooled to ambient temperature
2. 2
   ЭкстракцияThe mixture was extracted with EtOAc (3×200 mL)
3. 3
   Промывкаthe combined organic extracts were washed with brine (2×200 mL)
4. 4
   Концентрированиеconcentrated under reduced pressure
5. 5
   workup.ADDITIONThe residue was diluted in CH2Cl2 (100 mL)
6. 6
   Промывкаeluting with 10% EtOAc in hexanes (800 mL)
7. 7
   КонцентрированиеThe resulting filtrate was concentrated under reduced pressure
8. 8
   Другоеwas chromatographed over silica gel (Isco CombiFlash Rf unit, 3×330 g Redisep columns, 0% to 50% EtOAc in hexanes)

Методика

A mixture of tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate (6, 57.4 g, 185 mmol), 3 1-bromo-3,4-difluoro-2-(trifluoromethyl)benzene (48.5 g, 185 mmol), Pd(PPh3)4 (21.5 g, 18.5 mmol), and 2 M Na2CO3 (150 mL) in DME (500 mL) was heated to 80° C. for 16 h. The mixture cooled to ambient temperature and was diluted with 5% aqueous LiCl solution (100 mL). The mixture was extracted with EtOAc (3×200 mL), and the combined organic extracts were washed with brine (2×200 mL) and concentrated under reduced pressure. The residue was diluted in CH2Cl2 (100 mL) and sent through a 300 mL silica gel plug, eluting with 10% EtOAc in hexanes (800 mL). The resulting filtrate was concentrated under reduced pressure and was chromatographed over silica gel (Isco CombiFlash Rf unit, 3×330 g Redisep columns, 0% to 50% EtOAc in hexanes) to provide tert-butyl 4-(3,4-difluoro-2-(trifluoromethyl)phenyl)-5,6-dihydropyridine-1(2H)-carboxylate (7) as a white solid (59.0 g, 92%): 1H NMR (300 MHz, CDCl3) 57.34-7.28 (m, 1H), 6.93 (m, 1H), 5.55 (br, 1H), 4.01 (br, 2H), 3.60 (m, 2H), 2.30 (m, 2H), 1.50 (s, 9H); MS (ESI+) m/z 308 [M+H−C4H8]+.

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