Isocyanide, cyclohexyl

A series of 3-imino-2-aryl-l-azetines has been prepared by cycloaddition of nitrile ylides to isocyanides. Thus generation of the nitrile ylides (215) in the presence of cyclohexyl isocyanide gives the 3-cycIohexyIimino-2-aryI-l-azetines (205). Similar 1-azetines are formed by interception of nitrile ylides with a-methylbenzyl isocyanide (72AG(E)47) cf. Section 5.09.4.2.2). 

In contrast to the low stereoselections realized in the above syntheses utilizing imines of various chiral aldehydes79-8 1, an almost complete stereoselectivity is reported for the Ugi reaction of 2,3 4,5-bis-O-isopropylidenearabinose with ammonia, acetic acid and cyclohexyl isocyanide giving the 2-acetamino-2-deoxyglueono amides as the exclusive products84. 

Cyclohexyl isocyanide, 41,13 Cydopentadiene, conversion to sodium salt, 41, 96... 

Reactions of Pt(PPhj)2(R)X (R = CH3, C Hj X = Cl, Br, I) and methyl isocyanide 144) and analogous reactions of Pd(phos)2(CH3)I (phos = PPh3, PPhMc2) complexes with cyclohexyl isocyanide 169, 170) were reported about the same time. As might perhaps be anticipated, the platinum reactions were slower and one can isolate the intermediate species and observe their rearrangement to the inserted products [Eq. (8)]. The isolation of the... 

The addition of cyclohexyl isocyanide to several palladium(II) methyl complexes has proven particularly interesting 169, 170). From... 

Yamamoto and Yamazaki 171) carried out reactions of Pt(PEt3)2CHjI and Pt(PPhMe2)(CH2CjH5)I with tert-butyl and cyclohexyl isocyanides. These reactions gave small yields of the ionic intermediate species, which readily reverted to the appropriate iminoacyl complexes. In reactions of analogous chloride complexes the intermediate species was not isolated. It is suggested on the basis of PMR data that these iminoacyl complexes are five-coordinate (see above). 

Some infrared data on these catalytic systems also support the intermediate complex formation (123). For a heterogeneous system of Cu metal and cyclohexyl isocyanide one observes, in solution, a vcn absorption at 2180 cm , compared to 2140 cm for the free isocyanide. Absorptions at 2181 and 2192 cm for the systems with CujO and CuCl, respectively, are measured. The solutions in each case have catalytic activity. The suggestion is made that either a copper(O) complex (from Cu metal) or copper(I) isocyanide complex (from CU2O or CuCl) is the catalytic species present. 

In addition to a-additions to isocyanides, copper oxide-cyclohexyl isocyanide mixtures are catalysts for other reactions including olefin dimerization and oligomerization 121, 125, 126). They also catalyze pyrroline and oxazoline formation from isocyanides with a protonic a-hydrogen (e.g., PhCH2NC or EtOCOCHjNC) and olefins or ketones 130), and the formation of cyclopropanes from olefins and substituted chloromethanes 131). The same catalyst systems also catalyze Michael addition reactions 119a). 

Aumann and Fischer (7), as part of a larger project on carbene-metal complexes, have investigated the reaction of Cr(CO)5C(OCHj)CH3 and cyclohexyl isocyanide. They describe an initial 1 1 adduct of these reagents, to which they ascribe structure (XX) it is interesting to note that neither... 

Mono-substituted derivatives of [C5HjMn(NO)(CO)2] (32) and di-substituted (20, 146) derivatives of [CH3C5H4Mn(NO)(CO)2] have been prepared by direct reactions of the isocyanide and [C5H5Mn(NO)(CO)2] or [CH3CjH4Mn(NO)(CO)2]. Brunner and Schindler (32) observe variations of vqq and i no for the series [C5H5Mn(NO)(CO)L]+ (L = phosphines, and cyclohexyl isocyanide) in the order CNC H, > P(OPh)3->--->(PPh3)3 > PBuj. Reactions of the mono- and disubstituted complexes with pentafluorophenyllithium (20,146), and of the disubstituted species with borohydride (148) were noted above. 

The polymerization of allenes by [Rh(CO)2Cl]2 and a ligand (phosphines, arsines, amines, isocyanides) (175) and the polymerization of cyclohexyl isocyanide by Co2(CO)g (173) have been reported. 

The PMRs of several triscyclopentadienyl-lanthanide metal complexes of cyclohexyl isocyanide (C5H5)3MCNCgH, (M = Pr, Nd, Ho, Tm, Yb) are reported 159, 160). 

Methyl 4-formylbenzoate, benzylamine, 2-nitrobenzoic acid, and cyclohexyl isocyanide were converted to the corresponding 4CC Ugi adduct [16],... 

Other interesting multicomponent sequences utilizing isocyanides have been elaborated by Nair and coworkers. In a recent example, this group exploited the nucleophilic nature of the isocyanide carbon, which allows addition to the triple bond of dimethyl acetylenedicarboxylate (DMAD) (9-90) in a Michael-type reaction (Scheme 9.19) [59]. As a result, the 1,3-dipole 9-91 is formed, which reacts with N-tosylimines as 9-92 present in the reaction vessel to give the unstable iminolactam 9-93. Subsequently, this undergoes a [1,5] hydride shift to yield the isolable aminopyrroles 9-94. In addition to N-tosylimine 9-92 and cyclohexyl isocyanide (9-89), substituted phenyl tosylimines and tert-butyl isocyanide could also be used here. 

Mixed isocyanide/phosphine complexes can be obtained via several routes. The reaction of the suitable Tc starting material [TcH(N2)(dppe)2] (565) with excess CNBu in MeOH under reflux gave colorless traTO- Tc(CNBu )2(dppe)2] (566) in good yield. The j/cn IR bands appear at 2,049 cm and 2,079 cm for CNBu, and at 2,058 cm and 2,115cm for the corresponding cyclohexyl-isocyanide. The frequencies suggest a strong back-donation from Tc to isocyanide. Since... 

Another example of imidazo[2,l-b][l,3]thiazole formation was reported by Adib et al. in their publication concerning eco-friendly catalyst-free MCR in the water [133]. Reaction of cyclohexyl isocyanide with diverse aromatic aldehydes and 2-aminothiazoles in water at 70°C allowed the isolation of heterocycles 96 in good-to-excellent yields (Scheme 43). According to the spectral data, compotmds 96 were determined as single products of the MCR. 

The authors applied the similar methodology for a three-component reaction of dimethyl acetylenedicarboxylate, cyclohexyl isocyanide and several substituted ben-zaldehydes to obtain a small library of aminofurans (Scheme 9). Batch conversions reported in previous work required refluxing in benzene for 2-9 h [26] to achieve similar yields as reactions in dimethylformamide (DMF) under capillary flow using... 

Indole derivatives such as dihydroindolone are scaffolds of potentially biological interest. Thus, the development of such functionalized skeletons has been approached by a MCR involving cyclic 1,3-diketones, cyclohexyl isocyanide, aromatic aldehydes, and ammonium acetate in the presence of catalytic amount of KHSO4 in refluxing acetonitrile (Scheme 30) [117]. hi this strategy, the imine derived from the Knoevenagel adduct reacts with cyclohexyl isocyanide to give the... 

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. 

A facile one-pot synthesis of furopyrans takes place with aromatic aldehydes, cyclohexyl isocyanide, and 4-hydroxy-6-methyl-2-pyrone in the presence of a solid support such as Montmorillonite K-10 (Equation 62) <2005SC535>. The solvent-free reaction, which is enhanced by microwave irradiation, proceeds much more rapidly under these conditions than by conventional methods <2002TL2293>. The one-pot, three-component reaction is also reported to take place rapidly using water as solvent <2004M589>. 

Ein Beispiel fur die Mannich-Reaktion von Isocyaniden ist die zu Piperidino-essigsaure-cyclohexylamid (90%) fiihrende Umsetzung von Cyclohexyl-isocyanid mit Formaldehyd und Cyclohexylamin1. 

Diazadienes have been shown by various groups to be suitable precursors of imidazoline derivatives by means of [4 + 1 ] cycloaddition reactions. In 1976 Matsuda and co-workers were able to cycloadd heterodienes 303, available from AMrimethylsilyl benzophenone imine and phenyl isocyanate, with cyclohexyl isocyanide to obtain 305 in 91% yield, after methanolysis of the initial adduct 304 [76JCS(P1)1523] (Scheme 67). 

The disagreeable odor of cyclohexyl isocyanide can be removed from the equipment used in this preparation by washing it with 5% methanolic sulfuric acid solution. 

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