4-CHLORO-3-TRIFLUOROMETHYLPHENYLBORONIC ACID, PINACOL ESTER synthesis

Yield:445303-09-3 66%

Reaction Conditions:

with potassium acetate;PdCl₂(PPh₃)2 in 1,4-dioxane;ethyl acetate;

Steps:

2-(4-chloro-3-trifluoromethyl-phenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane

2-(4-chloro-3-trifluoromethyl-phenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane This compound was prepared in a modification of the literature known method (Y. Masuda, M. Murata, S. Watanabe, J. Org. Chem., 1997, 62, 6458-9). To a flask containing KOAc (3.4 g, 34.7 mmol), PdCl₂(PPh₃)₂ (234 mg, 0.34 mmol) and bis(pinacolato)diboron (3.2 g, 12.7 mmol) was added a solution of 5-bromo-2-chloro-benzotrifluoride (3 g, 11.5 mmol) in dioxane. This mixture was heated to 100° C. under an argon atmosphere for 3 h. After cooling, AcOEt was added then the organic mixture was washed with saturated NaCl solution then dried with Na₂SO₄ and the solvent evaporated. The residue was chromatographed (silica, elution with hexane/AcOEt=9:1) to afford the title compound (2.35g, 66%) as a light brown solid. MS: m/e=306.1 (M⁺).

References:

US2002/151715,2002,A1