Crotononitriles, reaction with

The reaction of acrylonitrile with ethanolic RhCls yields a product of approximate composition (CH2=CH—CN)2RhCl2 in which one of the acrylonitrile moieties is cr-bonded to Rh(III) and the other perhaps 7r-bonded as indicated by the chlorine-bridged structure (175) since it can be displaced by pyridine to yield (CH3CHCN)RhCl2(C5H5N)3 (168). The reaction is thought to involve an intermediate Rh(III) hydride. The comparable reaction with crotononitrile, methacrylonitrile, cinna-monitrile, methyl vinyl ketone, methyl vinyl sulfone, and isoprene does not occur (168). 

Unsaturated nitriles are formed by the reaction of ethylene or propylene with Pd(CN)2[252]. The synthesis of unsaturated nitriles by a gas-phase reaction of alkenes. HCN, and oxygen was carried out by use of a Pd catalyst supported on active carbon. Acrylonitrile is formed from ethylene. Methacrylonitrile and crotononitrile are obtained from propylene[253]. Vinyl chloride is obtained in a high yield from ethylene and PdCl2 using highly polar solvents such as DMF. The reaction can be made catalytic by the use of chloranil[254]. 

The other main type of reaction involves 6-aminouracils, which react with /3-amino-crotononitrile and aldehydes to give the 6-carbonitrile (277) (72KGS422), whilst from two moles of aminouracil with strong acids in DMF the back-to-back pyrimido fused molecule (278) is obtained (62USP3035061). 

A variety of four-membered ring compounds can be obtained with photochemical reactions of aromatic compounds, mainly with the [2 + 2] (ortho) photocycloaddition of alkenes. In the case of aromatic compounds of the benzene type, this reaction is often in competition with the [3 + 2] (meta) cycloaddition, and less frequently with the [4 + 2] (para) cycloaddition (Scheme 5.7) [38-40]. When the aromatic reaction partner is electronically excited, both reactions can occur at the 7t7t singlet state, but only the [2 + 2] addition can also proceed at the %% triplet state. Such competition was also discussed in the context of redox potentials of the reaction partners [17]. Most frequently, it is the electron-active substituents on the aromatic partner and the alkene which direct the reactivity. The [2 + 2] photocycloaddition is strongly favored when electron-withdrawing substituents are present in the substrates. In such a reaction, crotononitrile 34 was added to anisole 33 (Scheme 5.8, reaction 15) [41 ], and only one regioisomer (35) was obtained in good yield. In this transformation, the... 

The conversion of benzyl chloride to benzyl cyanide proceeded further than the soluble silacrovm. There is insufficient data to determine whether this is a general phenomenon. It has been pointed out by other workers7 that silica provides an adsorptive surface that can provide assistance in phase transfer. The reaction of potassium cyanide with allyl bromide under liquid/liquid phase transfer conditions produced a mixture of allyl cyanide and crotononitrile. This may be compared to the cataysis exhibited by another new phase transfer catalyst, immobilized trimethoxysilyloctyltributylammonium bromide, which produced only allyl cyanide. 

Other Addition Reactions - The photochemical addition in the gas phase of ammonia to a,P-unsaturated nitriles has been studied. The reactions are carried under conditions where all, or most, of the light is absorbed by the ammonia and this results in N-H bond fission and the production of NH2 radicals. These radicals add to the a-position of the substrate to yield 2-amino-propionitrile from acrylonitrile and analogous products are formed from crotononitrile, methacrylonitrile and 1-cyclohexenecarbonitrile. Additions also occur to but-2-yne nitrile which yields the Z, -isomers of 3-amino-crotononitrile with the E -isomer being predominant. The SET-induced amina-tion (using 1,4-dicyanobenzene as the sensitiser) of alkenylnaphthalene derivatives affords products of addition to both the alkene and the naphthalene skeleton. Suau et al. have examined the irradiation of phthalimide in the presence of low concentrations of hydroxide ion and alkenes. ° The result of this treatment is addition of the phthalimide moiety to the alkene. A SET... 

This reaction pathway is usually favoured when an aromatic moiety and an alkene bear electron-withdrawing and electron-donating substituents, respectively (or vice versa). This addition involves a charge transfer and the course of the reaction is sensitive to the solvent polarity. Such a mechanism may resemble that of [2 + 2] photocycloaddition of alkenes to aji-unsaturated carbonyl compounds (Section 6.3.2). Scheme 6.81 shows examples of two intermolecular processes and one intramolecular [2 + 2] photocycloaddition reaction (a) crotononitrile (196) is added to anisole (197) to yield several stereoisomers of 198 in 38% chemical yield and with high regioselectivity, which is linked to bond polarization in the exciplex 818 (b) hexafluorobenzene (199) reacts with 1-ethynylbenzene (200) to form the bicyclo[4.2.0]octa-2,4,7-triene 201 in 86% yield 819 and (c) irradiation of 202 in methanol leads to the single photoproduct 203. 820... 

Bromine added dropwise with stirring at 0° to a soln. of crotononitrile in abs. methanol, kept 12 hrs. at 0°, then allowed to stand 24 hrs. in the dark at 20°, the resulting soln. of the intermediate 2,3-dibromobutyronitriIe cooled, treated with 15%-NaOH, added to a soln. hydroxyurea in 10%-NaOH, shaken 40 hrs. at 20°, finally heated 2 hrs. on a water bath -> 3-amino-5-methylisoxazole. Y 1S%. F. e. with isolation of the intermediate ot,/ -dibromonitrile, and different course of the reaction, s. W. Klotzer et al., M. 101, 1109 (1970). 

Many other catalysts based on cobalt, ruthenium, rhodium, and platinum are now known to catalyze the hydrosilylation of alkenes, and the types of products can be controlled by the choice of catalyst and silane. Rhodium complexes, such as Wilkinson s catalyst, have been used frequently. A comprehensive treatment of selectivities is beyond the scope of this chapter, but several reviews provide information on the products formed from different catalysts and silanes.As one example, crotononitrile undergoes hydrosilylation in the presence of Wilkinson s catalyst to form the a-silyl nitrile product (Equation 16.23), and this regioselectivity contrasts with that for the reaction of the related acrylic acid ester in Equation 16.19 conducted with Speier s catalyst. 

In a typical example of this process, benzyl alcohol (3.0 mmol) was reacted with heptanol (1.0 mmol) in the presence of RuH2(CO)(PPh3)3 (4 mol%) combined with xantphos (4 mol%), silica-immobilized amine (0.9 mmol), and crotononitrile (5.0 mmol) as a hydrogen acceptor at 120 °C under microwave irradiation for 3 h to give the corresponding cross-coupled a,P-unsaturated aldehydes in 75 % yield (Scheme 39). In this reaction, the silica-immobilized amine was recycled (by simple filtration) at least five times without considerable loss in its catalytic activity. 

Kiricsi et al. [243,244] investigated the interconversion of unsaturated C4 nitriles (allyl cyanide, crotononitrile, and methacrylonitrile) under basic conditions. IR-spectroscopic studies of this reaction in butyl-lithium in the liquid phase [243] revealed the existence of resonance stabilized carbanionic intermediates. The investigation of this reaction over zeolite catalysts (Na-Y and Na-Y impregnated with NaNs to obtain strong basic sites) [244] suggests the presence of a common anionic intermediate, as in the case of the liquid phase reaction. The strongly basic Na/Na-Y was able to interconvert all nitriles, while the Na-Y catalyzed only double bond migration, i.e., interconversion of allyl cyanide and crotononitrile. 

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