Interaction Of Carbenes Research Articles

Halogen-containing heteroaromatic carbenes of the 1,2,4-triazole series and their transformations.

A series of new stable halogenated carbenes, 1-tert-butyl-3,4-diaryl-1,2,4-triazol-5-ylidenes, has been synthesized. According to quantum chemical calculations, 4-(2,3,4-trifluorophenyl)-substituted 1-tert-butyl-3,4-diaryl-1,2,4-triazol-5-ylidene is the least basic in comparison with the known sterically open stable heteroaromatic carbenes. Upon heating in organic solvents these carbenes undergo a tandem induced reaction thereby forming 5-amidino-1,2,4-triazoles. The interaction of carbenes with benzylidenemalononitrile, propanesultone and phenyl isothiocyanate results in zwitterionic compounds of the 1,2,4-triazole series. The data for X-ray diffraction study of 1-tert-butyl-3-phenyl-4-(2,4-difluorophenyl)-1,2,4-triazol-5-ylidene, its protonated salt, complex with copper(i) iodide, related complex of 1-tert-butyl-3-phenyl-4-(2-trifluoromethylphenyl)-1,2,4-triazol-5-ylidene, and adduct of 1-tert-butyl-3-phenyl-4-(4-bromophenyl)-1,2,4-triazol-5-ylidene and propansultone are given.

Interaction of Carbene and Olefin Donors with [Cl2PN]3: Exploration of a Reductive Pathway toward (PN)3

The iminophosphine-phosphazene [P(III)-P(V)] heterocyclic adduct [IPr·PN(PCl(2)N)(2)] was prepared via reduction of the cyclic phosphazene [Cl(2)PN](3) in the presence of the carbene donor IPr {IPr = [(HCNDipp)(2)C:], where Dipp = 2,6-(i)Pr(2)C(6)H(3)}. By contrast, the treatment of [Cl(2)PN](3) with the N-heterocyclic olefin IPr═CH(2) yielded the olefin-grafted phosphazene ring [(IPr═CH)P(Cl)N(PCl(2)N)(2)].

Aldehyde and Ketone Functions Further Substituted on Oxygen

AbstractFor Abstract see ChemInform Abstract in Full Text.

A quantum chemical study of the interaction of carbenes with 2-alkenylfurans and thiophenes

The study of the interaction mechanism of monoalkenyl-substituted furans and thiophenes with carbenes was performed by AM1 and MNDO methods. The energy profiles of two pathways were calculated, one leading to ylide formation and the second to cyclopropanation species. The insertion of methyl groups into the vinyl fragment does not change the energetic parameters of path 1. The reactivity of the exocyclic double bond was shown to depend on the degree of substitution. The calculations prove the presence of the intermediate ylide formation, based on experimental data. The stability of the ylides is determined by the heights of the cycloaddition barrier and the one of the reversed reaction 1 as shown by calculations.

Chain lengthening reaction on supported platinum catalysts. A novel aspect of the mechanism of homologation reactions and catalyst deactivation

Formation of toluene from n-hexane was observed on supported platinum catalysts and is discussed in terms of a surface depolymerization reaction connected with catalyst deactivation rather than the olefin–carbene interaction suggested earlier.