Trimethylsilyl isocyanide

Direct reaction of iron pentacarbonyl with trimethylsilyl isocyanide ( C=N—SiMe3) at 65°-75° yields an air-sensitive substitution product Me3Si—N=C Fe(CO)4 in 93% yield, with elimination of carbon monoxide (152). It was shown by infrared spectroscopy (38) that complex formation lowers the N=C bond order for Me3Si—N=C , whereas it raises the N=C bond order for Me3C—N=C , presumably as a result of interaction between dv orbitals of silicon with the metal d orbitals. 

Addition of electrophiles to electron-rich isocyanide complexes is a proven synthetic method for the synthesis of aminocarbyne complexes (5,6). Reaction of the trimethylsilyl isocyanide rhenium complex 34 with HBF4 was reported by Pombeiro and co-workers (68). It leads to loss of the trimethylsilyl group and formation of the parent aminocarbyne ligand CNHj [Eq. (28)]. The CNHj ligand is easily interconverted to the CNH... 

A multistep synthetic method has been reported for accomplishing hydrocyanation of various types of olefins that utilizes an organic isonitrile instead of HCN. The olefin is first treated with a stoichiometric quantity of Cp2Zr(H)Cl(Cp = it CsHj), followed by successive additions of t-butyl isocyanide and iodine. Trimethylsilyl isocyanide was also used as the CN source. 

It is noteworthy to emphasize that trimethylsilyl cyanide readily undergo equilibiroum with trimethylsilyl isocyanide under Lewis acid catalysis. Thus, it should be noted that the structure determination of the adducts must be carefully carried out. 

A completely different way of preparing isocyanides involves the reaction of epoxides or oxetanes with trimethylsilyl cyanide and zinc iodide, for example, ... 

Benzyne, which is generated in situ from 2-(trimethylsilyl)phenyl triflate and KF, acts as an alkyne congener in distannation in the presence of palladium-/ r/-alkyl isocyanide complex.157 A variety of substituted benzyne derivatives inserts into the Sn-Sn bond to give l,2-bis(stannyl)benzenes (Equation (59)). The reaction fails to occur in the presence of other palladium catalysts such as Pd(PPh3)4. 

Isopropylidene carbene (Me2C=C ) is generated efficiently from the enol triflate derived from iso-propyl trimethylsilyl ketone using KF/Aliquat [45], but full experimental details are not given. The carbene can be trapped by isocyanides to produce, after solvolysis, -substituted 3-methylbut-2-enoamides in 35-52% yield [46]. 

The cyanide ion is an ambident nucleophile and isocyanides may be side products. If the preparation of isocyanides is desired, they can be made the main products by the use of silver or copper(I) cyanide1577 (p. 368). Vinylic bromides can be converted to vinylic cyanides with CuCN,1578 with KCN, a crown ether, and a Pd(0) complex,1579 with KCN and a Ni(0) catalyst,15 1 or with K4Ni2(CN)6.1581 Tertiary halides can be converted to the corresponding nitriles by treatment with trimethylsilyl cyanide in the presence of catalytic amounts of SnCl4 RjCCl + Me3SiCN — R3CCN.1582... 

NMO NMP Nu PPA PCC PDC phen Phth PPE PPTS Red-Al SEM Sia2BH TAS TBAF TBDMS TBDMS-C1 TBHP TCE TCNE TES Tf TFA TFAA THF THP TIPBS-C1 TIPS-C1 TMEDA TMS TMS-C1 TMS-CN Tol TosMIC TPP Tr Ts TTFA TTN N-methylmorpholine N-oxide jV-methyl-2-pyrrolidone nucleophile polyphosphoric acid pyridinium chlorochromate pyridinium dichromate 1,10-phenanthroline phthaloyl polyphosphate ester pyridinium p-toluenesulfonate sodium bis(methoxyethoxy)aluminum dihydride (3-trimethylsilylethoxy methyl disiamylborane tris(diethylamino)sulfonium tetra-n-butylammonium fluoride f-butyldimethylsilyl f-butyldimethylsilyl chloride f-butyl hydroperoxide 2,2,2-trichloroethanol tetracyanoethylene triethylsilyl triflyl (trifluoromethanesulfonyl) trifluoroacetic acid trifluoroacetic anhydride tetrahydrofuran tetrahydropyranyl 2,4,6-triisopropylbenzenesulfonyl chloride 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane tetramethylethylenediamine [ 1,2-bis(dimethylamino)ethane] trimethylsilyl trimethylsilyl chloride trimethylsilyl cyanide tolyl tosylmethyl isocyanide meso-tetraphenylporphyrin trityl (triphenylmethyl) tosyl (p-toluenesulfonyl) thallium trifluoroacetate thallium(III) nitrate... 

Similar electroreductive silylation of a series of unsaturated nitrogen compounds such as trimethylsilyl cyanide, cyanamide or isocyanide, bis(trimethylsilyl)carbodiimide and trimethylsilyl isocyanate provide precursors of bis(trimethylsilyl)methylamine, which is useful for organic synthesis (equations 90 and 91)115. This electrochemical method is a safer and more economical process compared with the chemical process using an alkali metal such as lithium. 

Tris(trimethylsilyl)silane is found to be an efficient reducing agent for a variety of functional groups. In particular, the reduction of halides, chalcogen groups, thiono esters and isocyanides are the most common ones. The efficiency of these reactions is also supported by available kinetic data. The rate constants for the reaction of (TMS)3Si radicals with a variety of organic substrates are collected in Table 2. 

After the elucidation of the reaction of phenylisocyanide dichloride with phenyl(trimethylsilyl)phosphane, several other differently substituted isocyanide dichlorides react extremely slowly, so that high temperatures are necessary which prevent the... 

The story of the reaction of isocyanide dichlorides with bis(trimethylsilyl)phenylphosphane, however, does not end here. Like the reaction of t-butyl-bis(trimethylsilyl)phosphane with phosgene, the conversions with isocyanide dichlorides depend very much upon the reaction conditions. If the reaction is carried out at ambient temperature in a molar ratio of 1 1 in such a way that the isocyanide dichloride is rapidly dropped into the phos-phane solution, the hitherto unknown, 2,4-bis(phenylimino)-l,3-diphenyl-1,3-diphosphetanes are obtained besides the phosphinomethylenephosphanes. Several findings, suggest that their... 

Oxazoles with a free 2-position are metallated thereat by n-butyllithium, while 2,4,5-trimethyloxazole forms the anion (142) (81JOC1410). In the presence of a carboxyl or methoxycarbonyl group at C(4) the metallation is directed to the 5-position, even in the absence of a 2-substituent, to give, for example, the lithio compounds (143) and (144) (81TL3163). 2-Lithiooxazoles can equilibrate with open-chain isocyanides and the diphenyl compound has been trapped as a mixture of cis- and /rans-trimethylsilyl ethers (equation 9). 

Using a three-component palladium catalyzed reaction involving the isocyanides 86, allyl carbonates, and trimethylsilyl azide, 1-cyanoindoles 87 were prepared in moderate yields <02 JA11940. 

The intermediate 1,3-diphosphapropenes can be synthesized in a separate reaction of bis(trimethylsilyl)phosphanes with phosgene or isocyanide dichlorides (29, 99), respectively, and can be converted to the unsymmetrically substituted pentadienes with phosphaketene [Eq. (47)]. 

The first hints of the intermediate appearance of the 1-phospha-3-azaallenes, as one may call this class of compounds, were obtained during investigations of the system bis(trimethylsilyl)phosphane/ isocyanide dichloride. Depending to the course of reaction, bis(imino)-1,3-diphosphetane or 1,3-diphosphapropene is synthesized via addition of excess silylphosphane to the primarily formed monophospha-carbodiimode or its dimerization product (31). 

Benzoxazole, 2-trimethylsilyl-, -trimethylstannyl-, 56, 221 Benzoyl isocyanide, possible intermediate in fragmentation, 56, 80 Benzoylacetone, reaction with ethylenediamine, 56, 4 Benzoylation of uracils, photochemical, using diphenyl-l,3,4-oxadiazole, 55,... 

In a project on electron-deficient isocyanides, Lentz studied the reactivity of pentafluorophenyl isocyanide 4a, isocyanoacetonitrile 4b, pentacarbonylchromium diisocyanomethane 4c, and 2,2,2-trifluoroethylisocyanide 4d toward bis[tris(trimethylsilyl)methyl] diphosphene 3. Combination of the reactants in pentane or diethyl ether at ambient temperature led to the formation of the expected diphosphirane imines 5a-5d as yellow crystals in moderate yields (Equation 2). For the success of this process very bulky substituents at the P=P unit and electron-withdrawing groups at the nitrogen atom are required, which is evident by the decrease of thermostability in the series 5c m 5a >5b>5d <1998JFC73, 1999ZFA1934>. 

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