Condensation of aromatic acyl compounds with N,Ndimethylformamide diethyl acetal in a pressure tube under microwave heating gives 1-aryl-3-dimethylaminoprop-2-enones in almost quantitative yields. In the presence of hydrazine, these intermediates are transferred to the corresponding 3-arylpyrazoles.

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The reaction of VOCl 3 with tridentate rac-trans-[1-pyrazolyl-3-(2-pyridyl)]cyclohexanol in the presence of K 2 CO 3 generates a mononuclear six-coordinate V V complex. With the bidentate ligand rac-trans-2-(pyrazol-1-yl)cyclohexan-1-ol, reduction of V V to V IV takes place to give a dinuclear complex with bridging alkoxo units; this compound is also accessible

VOCl3 reacts with pyrazolylpyridines in the presence of tBuOH to give new six-coordinate vanadium oxoalkoxo complexes. Changing from tBuOH to tBuOOH does not lead to the corresponding tbutylperoxo complexes but to oxidation of Cl-, which finally results in chlorination of the pyrazole fragment of the chelate ligand. These new V(V) complexes catalyze the epoxidation of allylic alcohols and unfunctionalized olefins in the presence of tBuOOH.

The ring‐opening reaction of epoxycyclohexane with 2‐[3(5)‐pyrazolyl]pyridine results in the formation of racemic trans‐2‐[3‐(2‐pyridyl)‐1‐pyrazolyl]cyclohexanol (1). Kinetic resolution with lipase B from candida antarctica gives the (1S,2S) enantiomer of 1, the solid‐state structure of which was determined by X‐ray crystallography, as an enantiomerically pure tridentate ligand. Investigation by NMR spectroscopy of the corresponding oxodiperoxomolybdenum complex 2, where 1 acts as a bidentate chelate, proves the formation of a weak intramolecular MoVI(O2)····HO−C bridge in CHCl3 solution. This H bonding is broken by solvents such as acetone, THF or DMF, which are capable of forming hydrogen bonds to alcohols. Intermolecular hydrogen bonds between the OH groups and molybdenum peroxo moieties are also found in the solid‐state structure of 2, leading to a helical arrangement of the peroxo complexes.