A-Chloroacrylonitrile

Enamine addition to an unsaturated ester, followed by an intramolecular alkylation, provided a facile synthesis of an adamantane bis-/3-ketoester 674). Michael addition of pyrrolidinocycloheptene to other acrylic esters 668) and of other enamines to acrylic acids 675), a chloroacrylonitrile 676), and an unsaturated cyanocarboxamide (577) were reported. 

This reaction has recently been applied with success5 s for the modification of poly-(a-chloroacrylonitrile). As reported by the authors, the level of conversion of the nitrile groups into thioamide groups reaches 90%. 

The synthetic utility of the D-A reaction can be expanded by the use of dienophiles that contain masked functionality and are the synthetic equivalents of unreactive or inaccessible compounds. (See Section 13.1.2 for a more complete discussion of the concept of synthetic equivalents.) For example, a-chloroacrylonitrile shows satisfactory reactivity as a dienophile. The a-chloronitrile functionality in the adduct can be hydrolyzed to a carbonyl group. Thus, a-chloroacrylonitrile can function as the equivalent of ketene, CH2=C=0,63 which is not a suitable dienophile because it has a tendency to react with dienes by [2 + 2] cycloaddition, rather than the desired [4 + 2] fashion. 

Pyrroles are also formed from dipolarophiles such as a-acetoxy esters and a-chloroacrylonitrile that have potential leaving groups. 

Although the RIES mechanism of Scheme 3 fits the overall kinetic results, and is strongly supported by spectroscopic and chemical evidence presented below, there are loose ends . For example, k /k, the Y-intercept of Eq. 13, gives the partition between rearrangement of the excited diazirine (1 ) and its loss of nitrogen to carbene 2. It is difficult to see why this should depend on alkene identity, yet small dependences have been observed.19,33-37 The behavior can be understood in terms of the CAC mechanism (Scheme 2, Eq. 11), where the Y-intercept is dependent on the rate of rearrangement of the CAC. On the other hand, there are reports that the Y-intercept does not vary in experiments with benzylchlorocarbene and (e.g.) 1-hexene, a-chloroacrylonitrile, or TME.23... 

Subsequently, Watts and Goldstein expanded their initial report. For a-chloroacrylonitrile (a-CAN) 2/H H was found to vary monotonically with concentration decreasing upon dilution in solvents whose dielectric constant is less than that of a-CAN and increasing in solvents whose dielectric constant is greater than that of a-CAN. More limited data showed a similar apparent increase for VH H (at infinite dilution) in a series of vinyl halides (Table 19). Since VH H is known to be negative for the vinyl halides the apparent increase is an algebraic decrease in the absolute sense. 

The trend for AJ is in accord with the polarizability of the substituent atom, but opposite to the electronegativity trend. McLauchlan et al. 49> also studied a-CAN as a function of solvent and temperature. Their results, while differing in detail, are in accord with those of Goldstein s group. In a more recent study Goldstein et al. 5°) reexamined a-chloroacrylonitrile in detail in seven different... 

Watts, V. S., Reddy, G. S., Goldstein, J. H. The Variation of the H-H Coupling Constant and Chemical Shifts in a-Chloroacrylonitrile with Concentration and Solvent. 

Scheme 6.129 Products prepared from the 121- and 124-catalyzed stereoselective Michael additions of a-chloroacrylonitrile and acrylonitrile to a variety to cyclic a-cyanoketones and acyclic a-substituted cyanoesters.

Scheme 6.134 Exo-selective 121- and 124-catalyzed Diels-Alder reaction between a-chloroacrylonitrile and 3-hydroxypyran-2-one.

Various metal nitrates, represented by silver nitrate, sensitize photopolymerization of AN, methaciylonitrile, a-chloroacrylonitrile, croto-nitrile and methyl methacrylate. The efficiency of photosensitization runs nearly parallel to the ease of reduction of the metal ion. Although there is little doubt that the monomer plays some role in the photochemical process, it is rather difficult to decide whether the primary act is direct oxidation of the monomer or electron transfer between metal ion and nitrate anion. 

Transformation of a readily available heterocycle into a less readily available heterocycle is a time-honoured and valuable strategy in synthesis. In a recent example, a versatile and high yielding synthesis of trifluoromethylpyrroles was described, starting from trifluoromethyloxazolones. Typically, 2-trifluoromethyl-4-phenyl-5(2//) °xazolone was mixed with a-chloroacrylonitrile in methylene chloride at room temperature, triethylamine was added, and the mixture stirred. Standard work-up gave 3-cyano-2-phenyl-5-trifluoromethylpyrrole in 70% yield. 

In an attempt to use phenolic Mannich bases in a synthesis of 3-chromanones, a mixture of 1 -[(dimethylamino)methyl]-2-naphthol and a-chloroacrylonitrile was heated under reflux in anhydrous dioxane. The product, however, which was formed in 55% yield, was shown to be the naphthonaphthopyranopyran 1. 

Diels-Alder reaction of furanes.1 A number of copper and copper(II) salts can catalyze the cycloaddition of a-acetoxy- and a-chloroacrylonitrile to furane at 20-35°. 

Poly(a-chloroacrylonitrile) decomposes to low molecular weight compounds when treated with nucleophiles [A,iV-diethyldithiocarbamate (Et2NCS2 ), PhS and azide ions]. An2 SRN mechanism was suggested for this reaction, in which an ET to the polymer leads to a radical and chloride ion. Coupling with the nucleophile and decomposition are the main reactions proposed for the radical intermediates98. The reaction of 2-chloro-2-methylpropionitrile, as a model compound, with TV, A-diethyldithiocarbamate (52% yield) and PhS (61% yield) was studied98. 

Treatment of the enaminothione 217 (Ar = p-NC QH NR2 = pyrrolidino) with a-chloroacrylonitrile gives the dihydrothiapyran 218 with ethyl propiolate the thiapyran 219 is produced, which rearranges on standing to compound 220 by a [1.3] shift of the pyrrolidinyl group (equation 92)114. 

Balasubramanian, K. K. and Selvaraj, S., Novel reaction of o-phenolic Mannich bases with a-chloroacrylonitrile, J. Org. Chem., 45, 3726, 1980. 

Dipyrido[l,2-a 3, 3 -containing aluminum chloride (78CPB2924). 

A well-known example which underlines the vital advantage of this rate acceleration is the Cu(Bp4)2catalyzed [4 + 2] cycloaddition of a-chloroacrylonitrile (203) to the 5-substituted cyclopenta-diene (202). Owing to the selective coordination of the copper(I) ion with the nitrile group of (203), the desired adduct (204) was formed readily at 0 C, thus avoiding the otherwise dominating 1,5-rearrangement (202) (205) (Scheme 48). 

Pyridazino[3,4-i)]quinoxalines and pyrazolo[3,4-i)]qumoxalme hydrochloride are synthesized by the 1,3-dipolar cycloaddition reaction of 6-chloro-2-(l-methylhydrazino)quinoxaline 4-ox-ide with dimethyl or diethyl acetylenedicarboxylate and a-chloroacrylonitrile, respectively. ... 

In the same manner, 6-chloro-2-[2-(4-chlorobenzylidene)-l-methylhydrazino]quinoxaline 4-oxide reacts with a-chloroacrylonitrile to afford 2,3-dihydro-l//-l,2-diazepino[3,4-i)]quinoxalines. ° ... 

Ethylene dimethacrylate-methyl methacrylate Ethylene dimethacrylate 1,3-Butylene dimethacrylate Acrylonitrile a-Chloroacrylonitrile Vinyl acetate Styrene Vinyltoluene Divinylbenzene A -Vinyl-2-pyrrolidone 4-Vinylpyridine Diallyl phosphite Triallyl phosphate Butenediol... 

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