4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole → (S)-1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

Participants

Reaction Steps

A solution of 4-(4,4,5,5-Tetramethyl[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (9.24 g, 47.6 mmol), (R)-(−)-(2,2-Dimethyl-1,3-dioxolan-4-yl)methyl p-toluenesulfonate (15.00 g, 52.38 mmol) and CsHCO3 (23.3 g, 71.4 mmol) in anhydrous DMF (236 mL) was heated to 100° C. for 16 h. The reaction mixture was cooled to rt and partitioned between EtOAc and H2O. The aqueous layer was re-extracted with EtOAc (3×) and the combined organic fractions were washed with H2O (2×) and brine (2×), dried over Na2SO4, filtered and concentrated in vacuo resulting in the title compound as an orange oil which was used in the next step without further purification.

Provenance & Evidence