Cobalt catalyzed benzonitrile

The catalytic reaction may also be ctirried out using two different alkynes. For example, the co-cyclization of acetylene and propyne with acetonitrile yields a mixture of dimethylpyridines (lutidines) in addition to a-picoline and the isomeric collidines. The co-cyclization, however, turned out to be nonselective. For experimental details see [5 g]. The cobalt-catalyzed co-cyclization of benzonitrile and acetylene at 77 -Cp-cobalt cod gives 2-phenylpyridine in high yield. 

Kotora et al. extended the scope of the reaction and showed that cobalt-catalyzed [2+2+2] cyclotrimerization of diynes with benzonitrile is a convenient method to prepare bis-ort/zo-substituted arylpyridines (06T968). Pyridine 267 was oxidized to give 268. 

Notably, in the cobalt catalyzed aerobic oxidative amidation of toluene, Mizuno and co-workers discovered that benzonitrile was formed as the major product by using urea as nitrogen source [117]. When amorphous Mn02 was employed, the formation of benzamide turned to be the dominant process (Scheme 4.20). 

Cobalt(II) salts are effective catalysts for the oxidation of 1,2-glycols with molecular oxygen in aprotic polar solvents such as pyridine, 4-cyanopyridine, benzonitrile, DMF, anisole, chlorobenzene and sulfolane. Water, primary alcohols, fatty acids and nitrobenzene are not suitable as solvents. Aldehydic products are further oxidized under the reaction conditions. Thus, the oxidative fission of rram-cyclo-hexane-l,2-diol gives a mixture of aldehydes and acids. However, the method is of value in the preparation of carboxylic acids from vicinal diols on an industrial scale for example, decane-1,2-diol is cleaved by oxygen, catalyzed by cobalt(II) laurate, to produce nonanoic acid in 70% yield. ... 

Alkyne cyclotrimerization occurs at various homogeneous and heterogeneous transition metal and Ziegler-type catalysts [7], Substituted benzenes have been prepared in the presence of iron, cobalt, and nickel carbonyls [8] as well as trialkyl- and triarylchromium compounds [9]. Bis(acrylonitrile)nickel [10] and bis(benzonitrile)palladium chloride [11] catalyze the cyclotrimerization of tolane to hexaphenylbenzene. NiCl2 reduced by NaBH4 has been utilized for the trimer-ization of 3-hexyne to hexaethylbenzene [12]. Ta2Cl6(tetrahydrothiophene)3 and Nb2Cl6(tetrahydrothiophene)3 as well as 7 -Ind-, and 77 -Ru-rhodium... 

---