Isonitriles aromatic

Chalinidae 300-320 300-320 Adocia, Chalinula, Haliclona, Reniera Acetylenic derivatives, macro-heterocycles, triterpenes, sulfated meroterpenes, isonitriles, aromatic carotenoids, atypical sterols, long-chain phenols, pyridine derivatives, S/N heterocycles, cyclic peptides, sulfated derivatives... 

Several examples of [5C+1S] cycloaddition reactions have been described involving in all cases a 1,3,5-metalahexatriene carbene complex as the C5-syn-thon and a CO or an isocyanide as the Cl-synthon. Thus,Merlic et al. described the photochemically driven benzannulation of dienylcarbene complexes to produce ortho alkoxyphenol derivatives when the reaction is performed under an atmosphere of CO, or ortho alkoxyanilines when the reaction is thermally performed in the presence of an isonitrile [111] (Scheme 63). In related works, Barluenga et al. carried out analogous reactions under thermal conditions [36a, c, 47a]. Interestingly, the dienylcarbene complexes are obtained in a first step by a [2+2] or a [3S+2C] process (see Sects. 2.3 and 2.5.1). Further reaction of these complexes with CO or an isonitrile leads to highly functionalised aromatic compounds (Scheme 63). 

Tin-mediated-radical cyclization of isonitriles provides a useful strategy for the preparation of indoles (Fukuyama reaction).90 This radical cyclization is used for synthesis of 6-hydroxy-indole-3-acetic acid, which is the aromatic subunit of Nephilatoxin. The requisite isonitriles are prepared from nitroarenes via amines (Eq. 10.66).91... 

Lastly, Livinghouse s approach to the tricyclic core of 4 is highlighted by an acylnitrilium spirocyclization [19d], Exposure of isonitrile 48 to thiophenyl acetyl chloride provides an intermediate chloramine (49) that, in the presence of a silver salt, eliminates the chloride to form a nitrilium ion (R-N = C+-R). The nitrilium is attacked by the nucleophilic aromatic ring to furnish spirocyclic imine 50 in high... 

Other advances over the past few years have been the development of (a) homogeneous hydrogenation catalysts for substrates normally not readily reduced, e.g., aromatics, isonitriles, and nitro compounds, and (b) a number of catalyst systems with unusual selectivity properties, e.g., with the capability of reducing a,/3-unsaturated aldehydes to the corresponding a,/3-unsaturated alcohols (see Sections II,B,2 and VII). 

Jones and co-workers reported the ruthenium-catalyzed synthesis of indol derivatives in a single step starting from di-o,o -substituted aromatic isonitriles a representative example is shown in Scheme 77 366>366a... 

The Groebke-type multi-component reaction between 3-amino-l,2,4-triazole, aromatic aldehydes and benzylic isonitriles afforded iV-alkylidene-4//-imidazo[l,2-A [l,2,4]triazol-6-amines in moderate to good yields <2006TL6891>. 

The following compounds are unaffected by bis(p-methoxyphenyl) telluroxide dithi-olanes, enamines, aldehydes, ketones, alcohols, pyrroles, indoles, amino acids, aromatic amines, monohydroxyarenes, esters, hindered thiocarbonates, isonitriles, oximes, arylhy-drazones, sulphides, and selenides. ... 

Upon reaction of A -vinyliminophosphoranes (109) with aromatic isocyanates, vinylcarbodiimides (110) are formed, as shown in Scheme 47. Divi-nylcarbodiimides (111) can be obtained as side products (88CB271). With isonitriles the vinylcarbodiimides also afford pyrroles (112) via [4 + 1]-cycloaddition. Divinylcarbodiimide can also react via [4 -l- l]-cycloaddition with an isonitrile, whereupon an electrocyclic step of the initial diaza-1,3,5-trienes (113) follows. Finally, the pyrrolo[2,3-e]pyrazine 114 is obtained (88CB271). 

It was then demonstrated that the mixed aromatic and aliphatic isonitrile in 101 displays a differential reactivity at both ends. Ugi reaction of 101 with isopropylamine, isobutyraldehyde, and acetic acid yields the mono-Ugi... 

By carrying out the Ugi-reaction with a large number of isonitrils, aldehydes, carboxylic acids, and amines, it was found that formation of different products of the reaction occurred depending on the structure of the amines used. Thus, 3-aminoimidazoles 88 were isolated when aldehyde reacted with isocyanide and heterocyclic aromatic 2-aminoazine as primary amine (Scheme 38). 

Complexes resulting from an aromatic isonitrile and an aliphatic acetylide (Figure 7.8) are less stable, but the use of lateral substituents allows the formation of SmA and N phases at low temperatures [9]. 

The syntheses of iron isonitrile complexes and the reactions of these complexes are reviewed. Nucleophilic reagents polymerize iron isonitrile complexes, displace the isonitrile ligand from the complex, or are alkylated by the complexes. Nitration, sulfonation, alkylation, and bromina-tion of the aromatic rings in a benzyl isonitrile complex are very rapid and the substituent is introduced mainly in the para position. The cyano group in cyanopentakis(benzyl isonitrile)-iron(ll) bromide exhibits a weak "trans" effect-With formaldehyde in sulfuric acid, benzyl isonitrile complexes yield polymeric compositions. One such composition contains an ethane linkage, suggesting dimerization of the transitory benzyl radicals. Measurements of the conductivities of benzyl isonitrile iron complexes indicate a wide range of A f (1.26 e.v.) and o-o (1023 ohm-1 cm.—1) but no definite relationship between the reactivities of these complexes and their conductivities. 

The trimeric compounds have been cleaved with a variety of neutral ligands [Eq. (41)] (154). With PPh3 the reaction proceeds smoothly, the rate and extent of reaction being dependent on the nature of R (the process occurs more readily when R is aromatic), but with isonitriles species of indeterminate constitution are obtained in addition to lAu C(OR )=NR (CNR")]. The cyclic complexes also underwent stepwise oxidative addition of bromine or iodine to yield (155) mixed gold(I)-gold(III) species, and finally the analogous gold(III) trimers. 

The solid-supported reagent, 2, was subsequently used to convert isothiocyanates to isonitriles (Scheme 5.7). Primary, secondary and tertiary alkyl isocyanides, as well as aromatic analogues were synthesised using this microwave assisted methodology. Isocyamide products were produced in excellent yields and high purity in 30 min to 2 h at 140°C. 

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