Nucleophile reactions nitrile ylides

Reaction of iV-[(benzotriazol-l-yl)methyl]amide 707 with PCI5 gives chloroimine 708, which upon treatment with Bu OK is converted to nitrile ylide 709. Benzyl esters of ot,(3-unsaturated acids used as dipolarophiles trap species 709 to generate pyrroles 712 (Scheme 110) <2002JHC759>. When no trapping agent is added, the N-2 atom of benzotriazole act as a nucleophile, and tricyclic system 711 is formed <2001TL9109>. Addition of benzyl bromide... 

Cyclodditions to Carbon-Heteroatom Triple Bonds. Transient electrophilic carbenes are known to react with nitriles to give transient46 or even stable nitrile ylides 30.47 No reaction of transient nucleophilic carbenes with nitriles has been reported. 

We predicted that electron-rich 1,3-dipoles in addition to diazomethane, such as nitrile ylides, would react in this fashion as well, and in 1978, Padwa and Nobs reported just such a reaction, shown in the second equation in Fig. 30. This reaction also gives some [4 + 2] adduct, in which the most nucleophilic terminus of the dipole has added to the 6-position of the fulvene. We have also found that electron-rich dienamines add to fulvenes in high yield (third equation of Fig. 30)85 These results... 

Alternatively, initial nucleophilic addition of 384 to 385 gave rise to 386, which underwent internal deprotonation to generate a nitrile ylide 387. Conversion of 387 to 390 could occur via either of two pathways. In the first case, the nitrile ylide cyclized to a 5-(dialkylamino)-2-substimted oxazole 388. Reaction of 388 with a second equivalent of 385 would then afford 390. The authors showed that there was no reaction of an analog of 388 with a second equivalent of 385, thereby discounting this proposal. These results led the authors to conclude that 387... 

Type I There is an overlapping of the high-lying HOMO of the dipole with the LUMO of the dipolarophiles. Such a situation is often referred to as a HOMO-controlled dipole or a nucleophilic dipole and includes many commonly used dipoles such as azomethine ylide, carbonyl ylide, nitrile ylide, azomethine imine, carbonyl imine, and diazoalkane. There is a close similarity of these reactions with a normal electron-demand Diels—Alder reaction, which involves the overlapping of the diene HOMO and LUMO of the dienophile. 

Photo-triggered ring opening of 2//-azirines is a well-known reaction to produce pyrrolines [8, 71]. Padwa and co-workers showed that photoirradiation of azirines with a mercury arc lamp (450 W) equipped with Vycor filter generated the reactive nitrile ylide intermediate (72), which can be stabilized by the phenyl substituents. The nitrile ylide (72) then reacts with the electron-deficient olefins (73) such as acrylate and acrylonitrile in a cycloaddition reaction to form A -pyrrolines (74) (Scheme 10) [8]. Steenken and co-workers studied reaction kinetics of azirines with dipolarophiles as well as nucleophiles such as alcohols [72]. They showed that the reaction rate depends on the azirine substituents, the nucleophilicity of the reactant and the acidity of the alcohol. 

Decarboxylation of 1,3-dimethylorotic acid in the presence of benzyl bromide yields 6-benzyl-1,3-dimethyluracil and presumably involves a C(6) centered nucleophilic intermediate which could nonetheless have either a carbene or ylide structure. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been used to explore the gas-phase reactions of methyl nitrate with anions from active methylene compounds anions of aliphatic ketones and nitriles react by the 5n2 mechanism and Fco reactions yielding N02 ions are also observed nitronate ions are formed on reaction with the carbanions derived from toluenes and methylpyridines. 

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