2-Methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane → 1-[2-(oxan-2-yloxy)ethyl]-4-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-iodo-1-[2-(tetrahydro-pyran-2-yloxy)-ethyl]-1H-pyrazole (Stage 106.1.3, 8.50 g, 26.4 mmol) in THF at 0° C. under argon was added dropwise iPrMgCl 2 M in THF (26.4 ml, 52.8 mmol). The RM was stirred at 0° C. for 1 h. Then 2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Aldrich, Buchs, Switzerland, 6.25 g, 52.8 mmol) was added at 0° C. and the solution was stirred again and allowed to warm to rt for 1 h. After that, the RM was quenched with saturated aqueous NH4Cl (140 ml) and extracted with EtOAc (3×). The combined organic layers were washed with saturated aqueous NH4Cl, dried over Na2SO4, filtered and evaporated. The residue was purified by flash chromatography (hexane/EtOAc 5% to 45%). The fractions containing product were combined and evaporated to dryness to give the title compound as a colorless oil. (HPLC: tR 3.23 min (Method A); M+H=323 MS-ES)

Provenance & Evidence