Aryl isocyanides, reaction with

Ring closures which depend on the conversion of the heteroatom into an electrophile are mostly associated with the formation of thiophene, selenophene and tellurophene rings and some illustrative examples are shown in Scheme 17. The last example which concerns the conversion of reaction with isocyanides is of particular interest since it appears to entail the attack of an electrophilic nitrogen species on the aryl ring. 

Substantially more work has been done on reactions of square-planar nickel, palladium, and platinum alkyl and aryl complexes with isocyanides. A communication by Otsuka et al. (108) described the initial work in this area. These workers carried out oxidative addition reactions with Ni(CNBu )4 and with [Pd(CNBu )2] (. In a reaction of the latter compound with methyl iodide the complex, Pd(CNBu )2(CH3)I, stable as a solid but unstable in solution, was obtained. This complex when dissolved in toluene proceeds through an intermediate believed to be dimeric, which then reacts with an additional ligand L (CNBu or PPh3) to give PdL(CNBu )- C(CH3)=NBu I [Eq. (7)]. 

Reactions of the ferrocyanide ion with alkylating agents, and reactions of iron(II) salts with alkyl or aryl isocyanides, have led to complexes of several types including [FeLJ, [FeLjX], cis- and tranf-FeL4(CN)2 and FeL4X2 this chemistry is reviewed by Malatesta and Bonati (90). There has been some extension of this work. 

Reaction of the tetrasilanes with 1.5 equiv. of aryl isocyanide affords a four-membered ring product, in which all the Si-Si bonds and the carbon-nitrogen bond of the isocyano group are cleaved and reorganized (Equation (54)).135... 

Successive multiple insertions of an aryl isocyanide (ArNC) into the S-S bond of a diaryl disulfide (ArS)2 occurs in the presence of Pd(PPh3)4 to produce the corresponding poly(imino)alkane endcapped with an arylthio group (Equation (65)).167 Products of higher molecular weights are formed when isolated poly(imino)alkanes are again subjected to the conditions of the insertion reaction (up to n — 9). 

It has been shown that, in the presence of lithium diethylamide at —70 °C, bromoben-zoic acids form arynes which may react with arylacetonitriles to yield, predominantly, 2-cyanobenzoic acids. The reaction of alkyl and aryl isocyanides with benzyne may yield benzamide derivatives, showing their ability to act as charge-reversed equivalents to isocyanates. The generation and cyclization of a benzyne-tethered alkyllithium have been reported, and lead to a convenient synthetic route for 4-substituted indans. ... 

George and co-workershave investigated the reaction of cyclohexyl isocyanide (185) with DMAD and have shown that a major constituent of the product mixture is the 2 3 adduct (186) formed through a [6 -i- 4] addition of the initially formed intermediate (182) with the dipolar species (181, R = cyclohexyl). Thermal isomerization of 186 in refluxing xylene results in an isomeric spiro compound (187), whereas at higher temperatures, other valence isomers of 186 are formed (Scheme 29). - Winterfeldt had earlier isolated a 1 2 adduct (188) from the reaction of cyclohexyl isocyanide with DMAD. The reaction of some alkyl and aryl isocyanides with acetylenic esters in protic solvents, such as methanol, has been reported to give open-chain adducts with the incorporation of one or two solvent molecules. 

The use of a pyrimidine precursor continues to be the more popular approach to furo pyrimidines. The one-pot three-component condensation reactions of alkyl or aryl isocyanides with A[A -dimethylbarbituric acid in the presence of terephthaldialdehyde proceeded spontaneously at room temperature in DMF to give good yields of the corresponding l,4-bis(6-alkyl or arylamino-1,3-dimethylfurano[2,3-4]pyrimidin-2,4(l//,3//)-dione-5-yl)benzenes <2006BMCL3697>. 

EtSSEt (forming [Mo2Cl4(/i-SEt)2(dmpe)2]).162 Cleavage of Mo—Mo quadruple bonds has provided a useful synthetic route to several mononuclear compounds7 and, of special significance, are the reactions of alkyl and aryl isocyanides with Mo2+ compounds.163... 

Thermolysis of the formamidrazone 590, obtained from the reaction of hydrazine 488 with Vilsmeier salt 589, at 200°C or on boiling in nitrobenzene led, by intramolecular transformation, to the triazolo[4,3-c]pyrimidine 591 (90T3897). Aryl isocyanide dichlorides reacted with 488 in the presence of Et2N to give 3-anilinotriazolopyrimidines (592) (Scheme 117). 

Alkyl and aryl isocyanides are good ligands for gold(I) and many complexes are known. They can be prepared by reaction of the isocyanide with [AuCLtl- to give first [AuC13(RNC)], which is reduced by excess isocyanide to give [AuCl(RNC)].401-403 However, the preferred route is to displace SR2 from the complexes [AuX(SR2)] (equations 52 and 53).404 07... 

Interesting skeletal rearrangements are observed in the Pd-catalyzed reaction of tetrasilanes with 2,6-disubstituted aryl isocyanides [Eq. (28)].786,79... 

Benzoquinone, reaction with 6-amino-l,3-dimethyluracil, 55, 200 aryl isocyanides, 57, 5... 

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