Benzyl Bromide → 2-Benzyl-1,4,5,6-tetrahydro-cyclopentapyrazole-3-carboxylic acid amide

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Reaction Steps

To a solution of 1,4,5,6-tetrahydro-cyclopentapyrazole-3-carboxylic acid amide (41.5 g, 275 mmol) in THF (460 mL) at rt was added a solution of NaOH (5N aq., 110 mL, 0.54 mol). After stirring for 5 min benzyl bromide (49.2 g, 0.29 mol) was added and the reaction was stirred for 16 h. The volatiles were removed in vacuo and the resulting solid was washed with H2O (3×250 mL). Further concentration gave regioisomers of 1-benzyl-1,4,5,6-tetrahydro-cyclopentapyrazole-3-carboxylic acid amide and 2-benzyl-1,4,5,6-tetrahydro-cyclopentapyrazole-3-carboxylic acid amide (65.3 g, 270 mmol, 98% yield) as a 20:1 mixture and was used without separation).

Provenance & Evidence