Diisopropylamine → 1,3-Dimethyl-5-(tributylstannyl)-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

To a solution of LDA (prepared from diisopropylamine (3.6 mL, 1.1 equiv) and n-BuLi (1.6M in hexanes, 14.3 mL, 1.1 equiv) in THF (80 mL) at −78° C. was added dropwise a solution containing a 1:1 mixture of 1,3-dimethyl-1H-pyrazole and 1,5-dimethyl-1H-pyrazole (2 g, 1 equiv) in THF (5 mL) with keeping the temperature below −70° C. At the end of the addition, the mixture was stirred for 30 min at −78° C. before addition of tributyltin chloride (6.16 mL, 1.1 equiv) with keeping the temperature below −70° C. The mixture was then stirred at −78° C. for 30 min and at r.t. for 2 h. The mixture was poured into water and then extracted with AcOEt (3 times). The organic phases were combined, dried (Na2SO4) and concentrated in vacuo to give a yellow paste. The crude product was purified by flash chromatography (hexanes to EtOAc/hexanes (40:60)) to yield 1,3-dimethyl-5-tributylstannanyl-1H-pyrazole (2.88 g, 36%) as a colorless syrup. (TLC rf 0.46 in EtOAc/hexanes 20:80).

Provenance & Evidence