p-Toluenesulfonic acid monohydrate → 5-(5,5-Dimethylcyclopenten-1-yl)-1-methylpyrazole

Participants

Reaction Steps

A solution of the 2,2-dimethyl-1-(1-methyl-1H-pyrazol-5-yl)cyclopentanol (630 mg, 3.24 mmol) prepared in Example 99a and p-toluenesulfonic acid hydrate (2.00 g, 10.5 mmol) in toluene (20 mL) was stirred for 8 hours under reflux, and the solvent was subjected to azeotropic distillation with water. After allowing to cool, water (50 mL) was added to the reaction solution, and an organic layer was extracted. The thus obtained organic layer was dried over anhydrous sodium sulfate. After vacuum concentration, the residue was purified with silica gel chromatography (hexane/ethyl acetate=3:1) to yield the title compound (512 mg, 90%) as a brown oil.

Provenance & Evidence