Aromatic isocyanides

The addition of hydrogen fluoride to an aromatic isocyanide dichloride provides a route to the respective aryl-Af tnfluoromethyl amine [34] (equation 24)... 

Kim, B., Beebe, J.M., Jun, Y, Zhu, X.Y. and Frisbie, C.D. (2006) Correlation between HOMO Alignment and Contact Resistance in Molecular Junctions Aromatic Thiols versus Aromatic Isocyanides. Journal of the American Chemical Society, 128, 4970—4971. 

Samuel, D., Weinraub, B. and Ginsburg, D. (1956) Synthesis of several aromatic isocyanides. The Journal of Organic Chemistry, 21, ilh-iP. 

In a similar way (and as described for the aromatic isocyanides), aliphatic a, 3-un-saturated isocyanides can also be used, leading to similar structures with a cyclo-hexano instead of a benzo moiety [84]. Based on the approach using aromatic isocyanides, a small library of about 20 camptothecin derivatives has been prepared, of which irinotecan and topotecan have entered the clinical treatment of cancer [85]. For the synthesis of the camptothecin derivatives, 3-206 was alkylated with the appropriate propargylic bromides 3-207 to give 3-208, which were irradiated in benzene at 70 °C, together with the respective isocyanide 3-209 and hexamethylditin... 

Kim B, Beebe JM, Jun Y, Zhu XY, Frisbie CD (2006) Correlation between HOMO alignment and contact resistance in molecular junctions aromatic thiols versus aromatic isocyanides. J Am Chem Soc 128 4970 1971... 

Hwang, S. and Joo, S.-W. (2005) Binding property and structure of aromatic isocyanide self-assembly monolayers on Ag and Au surfaces. Surf. Interface Anal, 37, 294-9. 

Li, Y., Lu, D., Swanson, S.A.S.A., Scott, J.C. and Galli, G. (2008) Microscopic characterization of the interface between aromatic isocyanides andAu(lll) a first-principles investigation. J. Phys. 

Aromatic isocyanides can also be prepared conveniently by the dehydration of the corresponding formamides by phosphorus oxychloride, but much better results are obtained if the reaction is done in the presence of potassium fer/-butoxide rather than pyridine.6 Neither method of dehydrating formamides has yet been used to prepare methyl or ethyl isocyanide because their low boiling points make them difficult to isolate from the reaction mixture hence, until a suitable dehydration procedure is worked out, they are best made by reaction of the corresponding alkyl iodide with silver cyanide. ... 

A number of publications have appeared on the synthesis of cationic cobalt(I) complexes by known routes. The cations are of the well-established type [Co(CNR)5]+ (R = aryl) (119-122). Reactions of aromatic isocyanides with Co2(CO)g in refluxing toluene have given the fully substituted cobalt(O) dimer Co CNR) (R = xylyl, C6H2Me3-2,4,6, C6H2Br-4-Me2-2,6) (25,123). 

Insertions into the metal - oxygen bond in mercuric acetate with aromatic isocyanides has given the compound 119 (R = Ph, xylyl), which readily hydrolyzed to give organic acetamide derivatives (480). 

Among the features of Volume 41 is the smallest-scale synthesis yet published in Organic Syntheses, namely, the preparation of 0.0005 mole of cholestanyl methyl ether by a generally useful methylation procedure that employs diazomethane and fluoboric acid (p. 9). Two preparations of isocyanides by dehydration of formamides are included. One of these, illustrated by cyclohexyl isocyanide (p. 13), is most suitable for aliphatic isocyanides while the other, illustrated by o-tolyl isocyanide (p. 101), is most suitable for aromatic isocyanides. 

Nickel (0) and palladium (0) derivatives of this class are known. The nickel derivatives were first obtained by complete replacement of the carbon monoxide of Ni(CO)4 by aromatic isocyanides (PI, 96, 115, 116). With aliphatic isocyanides the reaction is more difficult. Hieber 91, 96) obtained the only trisubstituted methylisocyanide derivative, NiCO-(CNCH3)3, but recently Bigorgne 18, 21), who studied the reaction... 

Scheme 9 demonstrates the further synthetic application of the thus obtained N,0-acetals. Substitution of the alkoxy or acyloxy group by nucleophiles like enol ethers, enol esters, enamines, other electron-rich olefins, CH-acidic compounds, electron-rich aromatics, isocyanides, trimethylsilyl cyanide, organometallics, vinyl and allyl silanes, hydroxy functions, or trialkylphosphites either catalyzed by Lewis acids or proton acids leads to the product of the amidoalkylation reaction (path a). In the presence of stereocenters as control elements, diasteroselective amidoalkylation reactions can be performed as shown in a large number of examples. On the other side, as Nyberg showed for the first time [196], elimination with formation of enecarbamates [208] and enamides [196,208,209] followed by reaction with electrophiles or nucleophiles (path b) also is possible. 

In the presence of p-toluenesulfonic acid, hydrogen chloride, or triphenyl-methyl perchlorate, dimethyl sulfoxide oxidizes aliphatic and aromatic isocyanides to the corresponding isocyanates. The reaction is carried out at 50-80°, at which temperature dimethyl sulfide distils from the reaction mixture.12... 

Scheme 8.49 Functionalized amino mesoporous silica as an effective scavenger of sulfonyl chlorides, aromatic isocyanides and acid chlorides.

Amines react in general more readily than alcohols and aromatic isocyanides are more reactive than ahphatic ones. The ionic diisocyanide complexes react under milder conditions than the neutral monoisocyanide complexes . No reactions with mercaptanes have been reported. Acyclic aminocarbene complexes occur as isomers when R R due to restricted rotation around the C(carbene)—N bond . Dinuclear carbene complexes are formed when the amine complexes [Au(C6F5)NH2(CH2)nNH2] (n = 1 or 2) or the carbene complexes [(C6F5) ,AuC(NHR)NH(CH2)nNH2] (m = 1 or 3) are treated with the isocyanide compound [(C6F5)mAuCNR] (R = Ph or p-tolyl) . ... 

Figure 15 highlights a novel application of sp -CH activation. In this example, 7-methylindole is synthesized from an aromatic isocyanide derivative, via an intramolecular cyclization reaction. The suspected mechanism involves coordination of the ruthenium center to the C=N triple bond, followed by insertion into the benzylic C—H bond. Ru(dmpe)2(naphthyl)H (Chart 1) (dmpe = dimethylphos-phinoethane, a bidentate phosphine) is the catalytic system used (59). 

For the functionalized isocyanide compounds [(CO)5M(o-R3PCH2C5H4NC)]Bp4, the oxidation potentials are only marginally higher than those commonly found in related non-functionalized aromatic isocyanide complexes, thus indicating that the phosphonium group has not a substantial effect on the metal-centred anodic process, possibly as a result of its distance to the metal. 

The reaction scope was found to be very broad. Both aliphatic and aromatic isocyanides bearing either less-hindered or bulky substituent could undergo clean reactions with NSBVs to afford their corresponding products 6-12a-6-12n in good to excellent isolated yields under the Zn(OTf)2-catalyzed reaction condition... 

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