Nitrile Substituents

A 4-cyano substituted a-chloroalkyl)boronic ester (100) can be cyclized into the corresponding trans-2-boryl-l-cyanocyclobutane (102) by treatment with LDA (lithi- 

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The reactions of 2- and 4-cyanoquinazolines are similar to those of the chloro compounds. Thus the cyano group can be replaced by alkoxide, phenoxide, substituted amino, and hydrazino groups substitution of the 4-cyano takes place more readily than that of the 2-cyano group.The nitrile substituent can also be hydrolyzed to an alkoxycarbonyl and amide group/ ... 

The low reactivity of a-olefins such as propylene or of 1,1-dialkyl olefins such as isobutylene toward radical polymerization is probably a consequence of degradative chain transfer with the allylic hydrogens. It should be pointed out, however, that other monomers such as methyl methacrylate and methacrylonitrile, which also contain allylic C—H bonds, do not undergo extensive degradative chain transfer. This is due to the lowered reactivity of the propagating radicals in these monomers. The ester and nitrile substituents stabilize the radicals and decrease their reactivity toward transfer. Simultaneously the reactivity of the monomer toward propagation is enhanced. These monomers, unlike the a-olefins and 1,1-dialkyl olefins, yield high polymers in radical polymerizations. 

The physical and chemical properties of the X -phosphorins 118 and 120 are comparable to those of phosphonium ylids which are resonance-stabilized by such electron-pulling groups as carbonyl or nitrile substituents Thus they can be viewed as cyclic resonance-stabilized phosphonium ylids 118 b, c, d). As expected, they do not react with carbonyl compounds giving the Wittig olefin products. However, they do react with dilute aqueous acids to form the protonated salts. Similarly, they are attacked at the C-2 or C-4 positions by alkyl-, acyl- or diazo-nium-ions Heating with water results in hydrolytic P—C cleavage, phosphine oxide and the hydrocarbon being formed. 

Acrylonitrile graft polymerizes readily with either granular or pasted starch to yield starch-g-polyacrylonitrile (PAN), and reactions are generally carried out in water with ceric ammonium nitrate as the initiating system CL). Reaction of starch-g-PAN with alkali at elevated temperatures converts the nitrile substituents of PAN to a mixture of carboxamide... 

Methyl methacrylate (Fig. 1-4) and methacrylonitrile (6-5) are allylic-type monomers that do yield high molecular weight polymers in free radical reactions. This is probably because the propagating radicals are conjugated with and stabilized to some extent by the ester and nitrile substituents. The macroradicals are... 

Dipolar compounds such as those with chloro, nitro, and nitrile substituents are more strongly retained on cyano columns, compared to amino or diol [14]. Also, cyanopropyl silica can exhibit acidic or basic character, depending on the mobile phase used. It was shown that a complete reversal of elution order was obtained for phenol and anihne when MTBE and chloroform were used as the mobile phases, because phenol eluted first in the MTBE solvent and second in the chloroform solvent [9],... 

In general compounds possessing a substituent (Cl, C2IU, SCH-) beta to the nitrile substituent are less active against these insects than compounds with only hydrogens in this position. The only exception is for the first two entries in Table 2 where the chlorinated derivative appears to be somewhat more active on mites than its unchlorinated analogue. 

PAVs with nitrile substituents on the vinylene moieties can be prepared by Knoevenagel condensation of a dialdehyde 26 with a bisnitrile 27 as illustrated for the synthesis of CN-PPV (4) in Scheme 6.7 [7]. Both monomer components are readily prepared from the bischloromethyl compound 28 otherwise used as a monomer for a Gilch synthesis. Here also, molecular masses are lower than from Gilch synthesis. 

Most of the useful iodine transfer radical reactions arise from the addition of alkyl iodides, which have been activated by one or more adjacent carbonyl or nitrile substituents, to unactivated olefins. This both labilizes the initial iodide, facilitating chain initiation, and helps ensure that the atom transfer step is exothermic. The requisite iodides are typically synthesized by deprotonation with EDA or NaH, followed by iodination with I2 or A-iodosuccinimide. Cyclization of an iodoester yields primarily lactone product, proceeding through the intermediacy of the I-transfer products as shown in Scheme 5 [19]. Reactions in which a-iodoesters cyclized with alkynes also proved efficient. Similar ketones yielded less synthetically useful mixtures of cyclopentyl and cyclohexyl (arising from 6-endo transition states) products. 

The carbene or carbenoid derived from an a-diazocarbonyl compound cycloadds to nitriles to produce oxazoles with the nitrile substituent at C-2. 

Aminothiophene derivatives possessing an ortho-c thoay or nitrile substituent are good precursors for several heterocondensed thiophene systems. It is impossible to list all the different structures that have been synthesized by this procedure. Only a few examples are given below. Thieno[2,3-t/]pyrimidines have been made from 2-aminothiophene-3-carbonitrile and guanidine... 

Like former triazoles from Rohm and Haas, fenapanil and myclobutanil, fenbuconazole is chemically characterized by its nitrile substituent on the quaternary C2. Its synthesis [44] starts from the phenylethylation of phenylacetonitrile by 1-(2-bromoethyl)-4-chlorobenzene (Scheme 17.6). A second alkylation at the same carbon with dibromomethane then leads to a quaternary carbon still bearing a reactive bromomethyl group. Fenbuconazole is obtained as a mixture of enantiomers by nucleophilic substitution of the halogen by triazolyl sodium. 

Scheme 4. Deslongchamps creative use of a transannular Diels-Alder reaction as part of a total synthesis of (+)-maritimol (26) and model studies showing the influence of the nitrile substituent.

By designing suitable directing groups containing nitrile substituents, Yu et al. were able to devise an efficient chelation control for the functionalisation of toluene and hydrocinnamic acid derivatives, phenols, " and amines. 

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