Réaction #65242

Équation de réaction

1,2-dibromo-4,4-dimethylcyclopentene

4-fluorophenylboronic acid

ethanol

Na2CO3

→

1-(2-bromocyclopenten-1-yl)-4-fluorobenzene

Rendement 24.1%

Solvants

toluene

Conditions de réaction

Traitement

1. 1
   Températureat reflux overnight
2. 2
   Concentrationconcentrated in vacuo
3. 3
   workup.DISSOLUTIONThe residue was dissolved in ethyl acetate
4. 4
   Lavagewashed with water
5. 5
   Séchagedried (Na2SO4)
6. 6
   AutrePurification by silica gel chromatography (MPLC) with hexane

Mode opératoire

Under nitrogen, 1.3 g (5.1 mmol) of 1,2-dibromo-4,4-dimethylcyclopentene (Step 8) was reacted with 600 mg (4.3 mmol) of 4-fluorophenylboronic acid (Lancaster) in 23 mL of toluene, 15 mL of of ethanol, and 10 mL of 2M Na2CO3 in the presence of 250 mg (5 mol %) of Pd(PPh3)4. The reaction was vigorously stirred at reflux overnight and concentrated in vacuo. The residue was dissolved in ethyl acetate and washed with water, dried (Na2SO4), and reconcentrated. Purification by silica gel chromatography (MPLC) with hexane gave 250 mg of 1-(2-bromocyclopenten-1-yl)-4-fluorobenzene (38 in Synthetic Scheme X when R1 and R2 =CH3, R5 =F, and R3, R4, R6 and R7 =H) as a pale yellow oil which was reacted with 200 mg (1.2 mmol) of 4-methylthiophenylboronic acid (Example 1, Step 1) in 5.2 mL of toluene, 3.4 mL of ethanol, and 2.2 mL of 2H Na2CO3 in the presence of 40 mg (5 mol %) of Pd(PPh3)4. The reaction was vigorously stirred at reflux for 6 hours and concentrated in vacuo. The residue was dissolved in ethyl acetate and washed with water, dried (Na2SO4), and reconcentrated. Purification by silica gel chromatography (MPLC) with hexane gave 120 mg of 1-[2-(4-fluorophenyl)-4,4-dimethylcyclopenten-1-]-4-(methylthio)benzene (41 in Synthetic Scheme X when R1 and R2 =CH3, RS=F, R10 =SCH3, and R3, R4, R6, R7, R8, R9, R11, and R12 =H) as an oil: NMR CDCl3) δ1.20 (s, 6H0, 2.42 (s, 3H), 2.63 (s, 4H), 6.90 (t, J=8 Hz, 2H), 7.00-7.18 (m, 4H), 7.30-7.60 (m, 2H).

Source