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

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

This stage was prepared like described in patent application US 2007/0265272, p. 38 & 39: To a solution of 4-iodo-1-[2-(tetrahydro-pyran-2-yloxy)-ethyl]-1H-pyrazole (Stage 171.5, 7 g, 21.73 mmol) in anhydrous THF (55 mL) was added at 0° C. under argon iPrMgCl in THF (2 M, 21.73 mL) drop by drop. The RM was stirred at 0° C. for 1 h. Then 2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5.36 g, 32.6 mmol) was added at 0° C. and the solution was stirred at rt for 1 further hour. The RM was then quenched with 140 mL sat. aqueous NH4Cl and extracted with 3×150 mL EtOAc. The combined organic layers were washed with 70 mL sat. aqueous NH4Cl, dried over Na2SO4, filtered and evaporated to dryness. The residue was purified by flash chromatography (4×20 cm, Hexane/EtOAc 5%-40%) to afford the title compound as a colorless oil (tR 3.20 min (conditions 8), MH+=323).

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