Isonitriles, oxidation

Many novel cluster compounds have now been prepared in this way, including mixed metal clusters. Further routes involve the oxidative fusion of dicarbon metallacarborane anions to give dimetal tetracarbon clusters such as (103) and (104) O (jjg insertion of isonitriles into inetallaborane clusters to give monocarbon meiallacarboranes such as (105) and the reaction of small ii/t/o-carboranes with alane adducts such as Et3NAlH3 to give the commo species (106) ... 

The only known representative of this type of compound, 91, was prepared by 1,3-dipolar addition of mesityl nitrile oxide to telluroketone 85 (93JA7019 94MI1). The reaction proceeds smoothly on heating equimolar amounts of the reactants at 80°C, giving rise to 91 in 70% yield. The heterocycle is a thermally unstable and light-sensitive compound. Thermolysis of a deuterochloroform solution of 91 at 60-90°C in a sealed ampule affords 1,1,3,3-tetramethylindanone and mesityl isonitrile (94MI1). 

The first transition metal isonitrilate complex reported was the tetrahedral Co-1 complex [Co(C=NPh )4] where Ph = 2,6-Me2C6H3,96 characterized by a crystal structure analysis. Oxidation yields the zerovalent dimer Co2(C=NPh )8, which features two bridging isonitrile groups. 

A very common combination in Pd-catalyzed domino reactions is the insertion of CO as the last step (this was discussed previously). However, there is also the possibility that CO is inserted as the first step after oxidative addition. This process, as well as the amidocarbonylation, the animation, the arylation of ketones, the isomerization of epoxides, and the reaction with isonitriles will be discussed in this section. 

Although use of radio and stable isotope labels involving the trio of covalently-bonded nitrogenous functions in 3 and in 78, provided evidence that isocyano is the precursor of the isothiocyano and formamido groups [30, 81], it remains to be shown that a biosynthetic equivalent of the in vitro chemically-proven fusion process between isocyano and free sulfur (e.g., cf. Introduction) exists in the cells of sponges. In marine biota, various ionic forms of sulfur in a number of oxidation states, as well as organo-polysulfides are known. However, any association with the isonitrile group and a sulfated species has yet to be established. 

The 2,3-substituted indols are formed via a palladium-catalyzed coupling reaction of aryl halide, o-alkenylphenyl isocyanide, and amine (Equation (122)).481 Oxidative addition of an aryl halide, insertion of both the isonitrile and alkene moieties of o-alkenylphenyl isocyanide, and 1,3-hydrogen migration may form a 7r-allylpalladium species, which is then attacked by an amine to afford an indol. 

The acidity of the propargylic proton of the starting compound 18 allows the equilibration with the allene 19 induced by bases such as tertiary amines or alcoholates (Scheme 7.4). Such prototropic rearrangements furnish the title compounds 19 with at least one proton at the terminal carbon atom, often in good yields. The EWG group involves carboxylic acids [33], esters [34], ketones [35, 36], isonitriles [37], sul-fones [38], sulfoxides [39, 40] and phosphonates [41], The oxidation of easily accessi-... 

N-( 1-butyl-lithium, 1,1,3,3-tetramethylbutyl isonitrile, and deuterium oxide,... 

Guanidines have been prepared by the reaction between an amine, or an amine salt, and a host of other reagents, such as a thiourea in the presence of lead or mercuric oxide [83, 157, 158], carbodi-imides [140, 174, 175],calcium cyanamide [176, 177], isonitrile dichlorides [178—180], chloroformamidines [181], dialkyl imidocarbonates [182], orthocarbonate esters [183], trichloro-methanesulphenyl chloride [184], and nitro- or nitroso-guanidines [185-188]. Substituted ureas can furnish guanidines, either by treatment with amines and phosphorus oxychloride [189], or by reaction with phenylisocyanate [190] or phosgene [191]. 

As early as the 1960s, some syntheses based on the addition of nucleophilic reagents (vinyl magnesium bromide, HCN, isonitrile) on A-acyl trifluoroacetaldi-mines (fluoral imine) have appeared. The acidic function is further introduced by an appropriate oxidation or hydrolysis. These approaches have allowed preparation of higher fluoroalkylated homologues of trifluoroalanine and of nonracemic trifluor-oalanines (vide infra). However, preparation of the acyl imine of fluoral is rather... 

Compounds of palladium and platinum in zero oxidation state are no longer rare, but there is little or no structural information available. The best ligands seem to be isonitriles, tertiary phosphines, and tertiary arsines (162-164) compounds of platinum(O) with ammonia and ethylenedi-... 

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