CuCl catalysis

Phenyl isocyanates are generally more reactive than alkyl isocyanates in their reactions with alcohols, but with CuCl catalysis even alkyl isocyanates will react readily with primary, secondary, or tertiary alcohols (45-95% yield). ... 

In a variation, high yields of phosphonium salts (77%) have been claimed to be obtained from the reaction of white phosphorus and benzyl halides, XC Y nClA2 with the aid of metal or metal salt (CuCl) catalysis The reaction may also be carried out in a high boiling solvent. Here dialkylation prevails and tlie phosphinic acid (PhCH2)2P(O)OH is isolated after hydrolysis... 

In the presence of a catalytic amount of PdCh, Ar>,BiX2 (X=C1, OAc) couples with arylstannanes to give biaryls (Scheme 14.155) or, under a CO atmosphere, diaryl ketones (Scheme 14.156) [316]. Unsymmetrical biaryls are also prepared by Pd-catalyzed reaction of diaryliodonium salts with Ar3BiX2 [317]. Terminal acetylenes are phenylated by Ph3BiF2 under CuCl catalysis to afford phenyl-substituted acetylenes [318]. 

Conjugate addition. Under photoirradiation and CuCl catalysis enones are attacked by silylated nucleophiles (siloxyalkenes or alkylsilanes). 

The yields of 1,4-addition products from sec-butyl crotonate and Grignard reagents are improved by CuCl-catalysis provided that the catalyst is added to the Grignard reagent in small portions concurrently with the ester soln.— E n-Butylmagnesium bromide from n-butyl bromide and Mg in ether treated at 0 with ethereal scc-butyl crotonate and simultaneously with 1.4 mole-% CuCl in small portions over a period of 3 hrs. scc-butyl 3-methylheptanoate. Y 80 to 85%. F. e. s. J. Munch-Petersen and V. K. Andersen, Acta Chem. Scand. 15, 271, 293 (1961) cf. Org. Synth. 41, 60 (1961). 

In contrast to oxidation in water, it has been found that 1-alkenes are directly oxidized with molecular oxygen in anhydrous, aprotic solvents, when a catalyst system of PdCl2(MeCN)2 and CuCl is used together with HMPA. In the absence of HMPA, no reaction takes place(100]. In the oxidation of 1-decene, the Oj uptake correlates with the amount of 2-decanone formed, and up to 0.5 mol of O2 is consumed for the production of 1 mol of the ketone. This result shows that both O atoms of molecular oxygen are incorporated into the product, and a bimetallic Pd(II) hydroperoxide coupled with a Cu salt is involved in oxidation of this type, and that the well known redox catalysis of PdXi and CuX is not always operalive[10 ]. The oxidation under anhydrous conditions is unique in terms of the regioselective formation of aldehyde 59 from X-allyl-A -methylbenzamide (58), whereas the use of aqueous DME results in the predominant formation of the methyl ketone 60. Similar results are obtained with allylic acetates and allylic carbonates[102]. The complete reversal of the regioselectivity in PdCli-catalyzed oxidation of alkenes is remarkable. 

Another pathway takes place upon cyclization of hydrazides of benzene carboxylic acids in the presence of CuCl in an inert atmosphere in DMF. However, only the cyclization of hydrazide 76 (R = H) in conditions of copper catalysis makes it possible to isolate compound 77 (yield 20%). Other hydrazides of acetylenylbenzoic acids react to give a complex mixture of products (Scheme 132) (85IZV1367 85MI2). 

Further insight into the P-borylation reaction of a,P-enones (Scheme 2.32) showed that the reaction can be carried out in THF, and the catalyst generated in situ from CuCl (5 mol%), the imidazolium salt (5 mol%), and NaO Bu (10 mol%), to form the [Cu(O Bu) (NHC)] as the catalysis initiating species. In this case, stable boron enolate products are formed which need to be hydrolysed by methanol to the ketone products [114]. 

The conversion of ethylene to acetaldehyde using a soluble palladium complex, developed in the late 1950s, was one of the early applications of homogeneous catalysis and the first organo-palladium reaction practised on an industrial scale [40], Typically this reaction requires stoichiometric amounts of CuCl under aerobic conditions. The use of copper represents not only an environmental issue, but often limits the scope of ligands that can be used in conjunction with Pd. 

These reactions are subject to catalysis by certain transition metal ions and with small amounts of MnBr2 or CuCl the reaction proceeds satisfactorily with alkyl bromides.134... 

Entries 7 and 8 illustrate conversion of diazonium salts to phenols. Entries 9 and 10 use the traditional conditions for the Sandmeyer reaction. Entry 11 is a Sandmeyer reaction under in situ diazotization conditions, whereas Entry 12 involves halogen atom transfer from solvent. Entry 13 is an example of formation of an aryl iodide. Entries 14 and 15 are Schiemann reactions. The reaction in Entry 16 was used to introduce a chlorine substituent on vancomycin. Of several procedures investigated, the CuCl-CuCl2 catalysis of chlorine atom transfer form CC14 proved to be the best. The diazonium salt was isolated as the tetrafluoroborate after in situ diazotization. Entries 17 and 18 show procedures for introducing cyano and azido groups, respectively. 

Our group have developed 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO)-functionalized PEG for biomimetic oxidation of alcohols together with CuCl in compressed C02, through a so-called mono-phase reaction, two-phase separation process to recover the catalyst, thus leading to conducting a homogeneous catalysis in a continuous mode [62]. 

The exchange reaction of 1-bromonaphthalene with CuCl proceeds effectively in polar solvents, such as DMF or DMSO, at temperatures of 110-150 °C via a second-order mechanism. The reaction is reversible but the equilibrium favors formation of aryl chlorides. The catalysis is inhibited by chloride anion and by pyridine or, particularly, 2,2 -bipyri-dine. The ease of replacement decreased in the order Arl> ArBr> ArCl and the reactivity of the attacking nucleophile decreased in the order CuCl> CuBr> Cul. The exchange reac-... 

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