Benzyl isonitriles, preparation

Further alkylation of cyanopentakis(benzyl isonitrile) iron(II) bromide gave the hexaalkylated product, which was prepared independently by a different route. 

Hypobromite oxidation of 5-benzylaminotetrazole provides a useful preparation of benzyl-isonitrile. ... 

This method is particularly applicable to the more reactive benzyl halides which are easily hydrolyzed in the aqueous media usually employed for the metathetical reaction with alkali cyanides. For example, anisyl chloride treated with sodium cyanide in aqueous dioxane gives, as a by-product, 5-10% of anisyl alcohol as determined by infrared analysis. The use of anhydrous acetone not only prevents hydrolysis to the alcohol but also decreases the formation of isonitriles. This method was also applied successfully by the submitters to the preparation of -chlo-rophenylacetonitrile in 74% yield. 

Benzylic halides produce isonitriles (80-90%) with tetramethylammonium cyanoargentate, prepared from tetramethylammonium chloride and silver cyanide [20]. The reaction fails with simple haloalkanes. 

TFA-CH2CI2 [191]. Ugi 4CC products prepared in solution from the interconvertible isonitrile may be captured on a solid support by nucleophilic attack of the benzylic alcohol of resin 5e on the cyclic dipole that is formed in the presence of acid carboxylic acids can then be released from the resin by treatment with TFA [192]. 

Phenyl chlorothionoformate is presented as a versatile reagent for the preparation of nitriles and isonitriles under mild conditions [1130]. A general procedure is given for cyanides (see Section 4.5.1). Benzyl isocyanide and trrmethoxybenzyl isocyanide have also been prepared according to this procedure within 7.5-10 h at room temperature in yields of 82 and 85% [1130]. 

Compared with five-membered metallacycles, relatively fewer reports are known on the preparative methods and reaction chemistry of six-membered metallacycles. Whitby and coworkers have systematically investigated insertion of carbenoids into five-membered zirconacycles and developed a number of interesting six-membered zirconacycles [17, 26]. Isonitriles, 1-halo-l-lithioalkenes, allenyl carbenoids, allyl carbenoids, propargy carbenoids, benzyl carbenoids, and 1-nitrile-1-lithio epoxides can all insert into zirconacyclopentanes and zirconacyclopentenes to afford various six-membered zirconacycles (Eqs. 23,24). 

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