4,4,5,5-tetramethyl-2-propan-2-yl-1,3,2-dioxaborolane

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

Procedure: To a solution of 3-bromo-2-(4-fluorophenyl)-7-methyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine (1.5 g, 4.82 mmol, 1 eq) in THF (40 ml) is added a solution of n-Buli (3.314 ml, 1.6 M, 5.30 mmol, 1.1 eq) dropwise at −78° C. After 20 min of stirring, a solution of 1.23 g of 2-isopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.23 mmol, 1.1 eq) in THF is added dropwise and the reaction mixture is stirred for 2 hours at −78° C. Then the reaction mixture is quenched by the addition of an aqueous solution of NH4Cl and is extracted with EtOAc. The combined organic phases are washed with water and brine, dried over Na2SO4 and concentrated in vacuo. The crude is purified by silica gel chromatography (eluent cyclohexane/ethyl acetate). 760 mg (42%) of 2-(4-fluorophenyl)-7-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine are obtained. the reaction mixture is stirred for 2 hours at −78° C Then the reaction mixture is quenched by the addition of an aqueous solution of NH4Cl is extracted with EtOAc The combined organic phases are washed with water and brine dried over Na2SO4 concentrated in vacuo The crude is purified by silica gel chromatography (eluent cyclohexane/ethyl acetate)

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

Procedure: n-BuLi (1.2 equiv) is added to a solution of 2-bromo-4′,7′-diphenylspiro(fluorene-9,2′-indene) (6b) in anhydrous THF at −78° C. After stirring the mixture for 1 h, 2-isopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.5 equiv) is added. The reaction mixture is allowed to warm to room temperature and then is stirred overnight. The reaction mixture is mixed with a large amount of water for extraction with ether. The organic extracts are washed with brine before drying over anhydrous MgSO4. The crude product of 2-[4′,7′-diphenylspiro(fluorene-9,2′-inden)-2-yl]-4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane (7b) is purified by column chromatography on silica gel using methylene chloride as the eluent yielding a white powder (79%). is stirred overnight The organic extracts are washed with brine before drying over anhydrous MgSO4 The crude product of 2-[4′,7′-diphenylspiro(fluorene-9,2′-inden)-2-yl]-4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane (7b) is purified by column chromatography on silica gel

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

Procedure: To a solution of 3-bromo-2-(4-fluorophenyl)-7-methyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine (1.5 g, 4.82 mmol, 1 eq) in THF (40 ml) is added a solution of n-Buli (3.314 ml, 1.6 M, 5.30 mmol, 1.1 eq) dropwise at −78° C. After 20 min of stirring, a solution of 1.23 g of 2-isopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.23 mmol, 1.1 eq) in THF is added dropwise and the reaction mixture is stirred for 2 hours at −78° C. Then the reaction mixture is quenched by the addition of an aqueous solution of NH4Cl and is extracted with EtOAc. The combined organic phases are washed with water and brine, dried over Na2SO4 and concentrated in vacuo. The crude is purified by silica gel chromatography (eluent cyclohexane/ethyl acetate). 760 mg (42%) of 2-(4-fluorophenyl)-7-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine are obtained. the reaction mixture is stirred for 2 hours at −78° C Then the reaction mixture is quenched by the addition of an aqueous solution of NH4Cl is extracted with EtOAc The combined organic phases are washed with water and brine dried over Na2SO4 concentrated in vacuo The crude is purified by silica gel chromatography (eluent cyclohexane/ethyl acetate)