Nickel-catalyzed cyanation

Nickel-catalyzed carbonylation of a-ketoalkynes has also been reported by Arzoumanian et al. under phase-transfer conditions.94 The carbonylation gave either furanone or unsaturated carboxylic acids depending on the substituents of substrates (Eq. 4.53). A similar reaction, nickel-catalyzed cyanation of a-ketoalkynes with KCN in water, was also reported to afford unsaturated hydroxylactams (Eq. 4.54).95... 

Later, a nickel-catalyzed cascade conversion of propargyl halides and propargyl alcohol into a pyrone in water was reported. The reaction involved a carbonylation by CO and a cyanation by KCN (Eq. 4.55).96 Recently, Gabriele et al. explored a facile synthesis of maleic acids by palladium catalyzed-oxidative carbonylation of terminal alkynes in aqueous DME (1,2-dimethoxyethane) (Eq. 4.56).97... 

The nickel-catalyzed transformation of aromatic halides into the corresponding nitriles by reaction with cyanide ions is reported. Both tris(triarylphosphine)nickel(0) complexes and tY2ins-chloro( aryl )bis( triarylphosphine )nickel(II) complexes catalyze the reaction. The influence of solvents, organophos-phines, and substituents on the aromatic nucleus on catalytic cyanation is studied. A mechanism of the catalytic process is suggested based on the study of stoichiometric cyanation of ti3ins-chloro(aryl)bis(triphenylphosphine)nickel-(II) complexes with NaCN and the oxidative addition reaction of Ni[P(C6H5)3]s with substituted aryl halides. 

Tris (triphenylphosphine) nickel, tris (tri-p-tolylphosphine) nickel, and bis (1,3-diphenylphosphinepropane) nickel proved to be good catalysts, the first being slightly more effective. The tricyclohexylphosphine complex was a very poor catalyst, and bis (cyclooctadiene) nickel did not catalyze cyanation. Cyanation of several substituted aromatic halides in the presence of Ni[P(C6H5)3]3 prepared by reducing dichlorobis (triphenylphosphine) nickel (II) 2 with a powdered manganese iron (80 20) alloy (Reaction 3) is reported in Table II. 

Palladium-catalyzed carbonylation of aryl triflates in the presence of an alcohol141 or amine1423 provides a good method for preparation of arenecarboxylic esters and amides from phenols (equation 121). However, palladium-catalyzed cyanation of 5,6,7,8-tetrahydro-2-naphthyl triflate with potassium cyanide failed completely whereas the more reactive tetrakis(triphenylphosphine)nickel(0) could catalyze the same reaction which gives the nitrile in a good yield142b (equation 122). 

Application of Transition Metal Catalysts in Organic Synthesis, Springer, Berlin, 1998, 149-178. Nickel- and Palladium-Catalyzed Cyanation of sp -Halides and sp -Trillates. 

Table I. Cyanation of l-Chloronaphthalene° Catalyzed by Nickel(0) Complexes in Ethanol6 at 60°C...

Cyanation Catalyzed by Nickel(O) Complexes. Results of cyanation of 1-chloronaphthalene with NaCN in ethanol using various nickel(O) complexes as catalysts are shown in Table I. 

Cyanation Catalyzed by trans-CHLORO ( aryl ) bis ( triphenylphos-phine) nickel (II) Complexes. In Table III cyanation of aryl halides catalyzed by the Ni(II) complexes obtained by reaction between aryl halides and Ni[P(C6H5)3]3 (Reaction 2) is shown. In general the trans-chloro (1-naphthyl) bis (triphenylphosphine) nickel (II) complex was used. Ortho substituted aryl halides were allowed to react in dimethylformamide... 

Ethyl 3-formylbutyrate (61) was prepared in 15% overall yield from ethyl crotonate (56) by sequential hydrobromination, cyanation, reductive amination with 7V,7V -diphenylethylenediamine (59) in the presence of Raney nickel catalyst, and acid-catalyzed hydrolysis as shown in Scheme... 

This reaction was modified by the replacement of CuCN with cheaper NaCN in the presence of palladium or nickel catalyst, as exemplified by the 5% Pd(PPh3)4/10% Cul catalyzed reaction and the Ni(CN)2 or NaCN/NiBr2 based reaction under microwave irradiation for aryl bromide. The latter condition is also used for the cyanation of aryl chloride with NaCN and NiBr2. In addition, this reaction has also been extended to the preparation of some Qf,)0-unsaturated nitriles. Further modifications include the copper-catalyzed domino halogen exchange-cyanation and the application of ionic liquid as reaction media. ... 

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