4-(Ethylsulphonyl)benzeneboronic acid → 2-(4'-Ethylsulfonyl-6-fluorobiphenyl-3-yl)-2,3-dihydro-1H-1,3-diaza-2-boraphenalene

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Reaction Steps

To a room temperature solution of 4-(ethylsulphonyl)benzeneboronic acid (0.90 g, 4.22 mmol) in anhydrous DMF (20 mL) was added 2-(3-chloro-4-fluorophenyl)-2,3-dihydro-1H-1,3-diaza-2-boraphenalene (Preparation 81, 1.00 g, 3.37 mmol) and potassium phosphite (2.87 g, 13.5 mmol) and the reaction mixture was degassed with argon for 30 minutes. To this was added 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (276.7 mg, 0.67 mmol) followed by the tris(dibenzilideneacetone)palladium(0) (154 mg, 0.168 mmol) and the resultant solution was heated to 100° C. with stirring for 12 hours. The reaction mixture was cooled then filtered through a pad of celite. The pad was rinsed well with EtOAc (100 mL) and the filtrate was washed with water (2×50 mL) then saturated brine solution and dried over anhydrous MgSO4 (s), filtered and evaporated in vacuo to give crude product as a yellow oil. The residue was purified by silica gel column chromatography eluting with CH2Cl2:MeOH 98:2 to afford the title compound as a colourless oil in 42% yield, 600 mg.

Provenance & Evidence