1-bromo-2,3-dimethylbut-2-ene

Conditions: temp:90.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 1-Bromo-2,3-dimethylbut-2-ene (3.78 g, 23.19 mmol), and cesium carbonate (15.11 g, 46.4 mmol) were added to a solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (3.0 g, 15.46 mmol) in DMF (52 mL), and the mixture was stirred at 90° C. for 18 h. The mixture was allowed to cool to room temperature, diluted with diethyl ether, washed with water (3×50 mL) and brine. The organic layers were separated, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (0-40% EtOAc/hexane) to afford 1-(2,3-dimethylbut-2-en-1-yl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole. 1H NMR (500 MHz, CDCl3) δ 7.79 (s, 1H), 7.62 (s, 1H), 4.74 (s, 2H), 1.83 (s, 3H), 1.74 (s, 3H), 1.59 (s, 3H), 1.31 (s, 12H). to cool to room temperature washed with water (3×50 mL) and brine The organic layers were separated dried over anhydrous magnesium sulfate concentrated under reduced pressure The residue was purified by column chromatography on silica gel (0-40% EtOAc/hexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: On a three neck flask containing 50 ml of dry THF, at −70° C., were added 65 ml of a 1.5 M solution of LDA THF in cyclohexane (96 mmoles). To said solution were added, dropwise, 10 g of 2,4-dimethyl-3-pentanone (87.5 mmoles). After one hour stirring, the medium temperature was left to warm up to 0° C., and then 14.3 g of 2,3-dimethyl-1-bromo-2-butene (87 mmoles) were added dropwise so as to maintain the reaction temperature between 0° and 10° C. At the end of the addition of the bromide, the temperature was risen to room temperature. After one hour stirring the reaction medium was poured into an excess of a 2 M aqueous HCl solution. The mixture thus obtained was extracted with 100 ml of cyclohexane and the organic layer washed with water until neutrality. were added the medium temperature was left to maintain the reaction temperature between 0° and 10° C was risen to room temperature After one hour stirring the reaction medium The mixture thus obtained was extracted with 100 ml of cyclohexane the organic layer washed with water until neutrality

Conditions: temp:90.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 1-Bromo-2,3-dimethylbut-2-ene (3.78 g, 23.19 mmol), and cesium carbonate (15.11 g, 46.4 mmol) were added to a solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (3.0 g, 15.46 mmol) in DMF (52 mL), and the mixture was stirred at 90° C. for 18 h. The mixture was allowed to cool to room temperature, diluted with diethyl ether, washed with water (3×50 mL) and brine. The organic layers were separated, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (0-40% EtOAc/hexane) to afford 1-(2,3-dimethylbut-2-en-1-yl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole. 1H NMR (500 MHz, CDCl3) δ 7.79 (s, 1H), 7.62 (s, 1H), 4.74 (s, 2H), 1.83 (s, 3H), 1.74 (s, 3H), 1.59 (s, 3H), 1.31 (s, 12H). to cool to room temperature washed with water (3×50 mL) and brine The organic layers were separated dried over anhydrous magnesium sulfate concentrated under reduced pressure The residue was purified by column chromatography on silica gel (0-40% EtOAc/hexane)