Methyl 3-bromopropanoate → Methyl 3-[4-(3,5-dichlorobenzyl)-3,5-diethyl-1h-pyrazol-1-yl]propanoate

Participants

Reaction Steps

A solution of the pyrazole of Example 11 (198 mg, 0.70 mmol) in ethanol (1 ml) was treated with sodium ethoxide (21% w/v, in EtOH) (261 μL, 0.81 mmol) and then methyl-3-bromopropionate (153 μL, 1.40 mmol) and heated at 70° C. in a sealed Reacti-vial (Trade Mark) for 18 hours. Over a period of 3 days more sodium ethoxide (2.65 eq) and methyl-3-bromopropionate (6.0 eq) were added and the reaction was maintained under the same conditions. After cooling, the solution was concentrated under reduced pressure. The residue was partitioned between dichloromethane and water. The organic phase was dried over anhydrous magnesium sulphate, filtered and concentrated under reduced pressure. The crude material was purified by flash chromatography on silica gel eluting with pentane:ethyl acetate (5:1, by volume) to afford two products.

Provenance & Evidence