Copper -3,5-dimethylpyrazole

Whereas the condensation of o-iodonitrobenzene with copper acetylides is accompanied by cyclization into isatogens, neither 4-iodo-3-nitro- nor 5-iodo-4-nitro-l,3-dimethylpyrazole gives cyclized products in conditions of acetylide synthesis. Moreover, nitropyrazolylphenylacetylene, as compared with o-nitrotolane, does not undergo thermal, catalytic, or photochemical isomerization to give the fused five-membered rings. 

We employed malononitrile and l-crotonoyl-3,5-dimethylpyrazole as donor and acceptor molecules, respectively. We have found that this reaction at room temperature in chloroform can be effectively catalyzed by the J ,J -DBFOX/Ph-nick-el(II) and -zinc(II) complexes in the absence of Lewis bases leading to l-(4,4-dicya-no-3-methylbutanoyl)-3,5-dimethylpyrazole in a good chemical yield and enantio-selectivity (Scheme 7.47). However, copper(II), iron(II), and titanium complexes were not effective at all, either the catalytic activity or the enantioselectivity being not sufficient. With the J ,J -DBFOX/Ph-nickel(II) aqua complex in hand as the most reactive catalyst, we then investigated the double activation method by using this catalyst. 

JV-(2-HYDROXYETHYL)-3,5-DIMETHYLPYRAZOLE, A DINUCLEAR COPPER COMPLEX, AND N-(2-p-TOLUENESULFONYLETHYL)-3,5-DIMETHYLPYRAZOLE... 

Figure 4-35. The copper(n) mediated reaction of cyanate with 3,5-dimethylpyrazole.

In the case of amine nucleophiles, the products from the reaction with co-ordinated cyanates are carbamates or ureas (Fig. 4-34), and this provides a particularly convenient method for the preparation of carbamate complexes. An example of this behaviour is seen in the reaction of 3,5-dimethylpyrazole with cyanate in the presence of copper(n) salts (Fig. 4-35). Similar reactions are observed with co-ordinated thiocyanates and other heterocumulene s. 

It is possible to use ancillary ligands in addition to phosphonic acids in building up nanosized cluster compounds of late transition metal ions. Thus, the reaction of CuCl2 with tert-butylphosphonic acid in the presence of 3,5-dimethylpyrazole affords a dodecanuclear copper phosphonate with an interesting cage structure,3 Similarly, large vanadium phosphonate clusters with up to 18 vanadium atoms have been assembled from phosphonic acids.35... 

A novel soluble complex, (t/ -ethene)hydrotris(3,5-dimethylpyrazol-l-yl)boratocopper(I) (3) mediates the cyclopropanation of styrene, hex-1 -ene, and cyclooctene with ethyl diazoacetate in 76 96% yield (25 C, 1 mol% of catalyst).Copper complexes with the tridentate 2,6-bis[(5-oxo-2,5-dihydropyrrol-2-ylidene)methyl]pyridine ligand or homologous tetradentate l,T-bipyridine and l,T-biisoquinoline ligands are also suited to cyclopropanation of styrene with ethyl diazoacetate. 

In the five-coordinate [Cu(Tp )L]C104 (L = 1-methylcarbal-dimino-3,5-dimethylpyrazole) characterized by IR, UV-Vis, EPR, and cyclic voltammetry, copper is in a distorted square-pyramidal geometry coordinated by tridentate K3-Tp and two N atoms from L.543... 

Reaction of polymeric copper(H-3,5-dimethylpyrazolate (dmpz) suspended in wet CH2CI2 with dioxygen gives [Cu(dmpz)(OH)]g. The cage contains a planar ring of copper(II) centers, with each Cu Cu vector bridged by a dmpz and hydroxide. No magnetic data are reported for the compound. 

Two new ligands N,N-bis(3,5-dimethylpyrazol-l-ylmethyl)benzylamine, bpmba, and N,N,N, N tetrakis(3,5-dimethylpyrazol-l-ylmethyl)-a,a -diamino-/n-xylene. bpmdx have recently been synthesized [26] their copper complexes are active catalysts for the oxidation of catechol to 0 benzoquinone. 

N-(2-hydroxyethyl)-3,5-Dimethylpyrazole, a Dinuclear Copper Complex 83 Starting Materials... 

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