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Cyano-ketones => nitriles

The cyano ketone 89 is converted into the nitrile 90 by heating at 140 C with Pd(Ph3P)4[73,74]. The a-lcetophosphonate 91 is decarbonylated with PdMe2(PMePh2)2 complex to give the phosphonate 92[75]. [Pg.538]

The second cycloaddition substrate took to form of 91 (Scheme 1.9b), incorporating a vinyl sulfone dipolarophile. Beginning with cyano ketone 84, which was readily prepared from 1,5-dicyanopentane via a previously reported three-step sequence [45], condensation with thiophenol produced vinyl sulfide 85 in 84 % yield. Vinyl sulfide 85 underwent bromination in acetonitrile to afford bromo-vinyl sulfide 86 (86 %), which was then treated with isopropylmagnesium chloride [46] to effect metal-halogen exchange affording an intermediate vinyl magnesium bromide species. Subsequent alkylation with Mel in the presence of catalytic CuCN provided the alkylated vinyl sulfide 87 in 93 % yield. The nitrile within vinyl... [Pg.11]

Ketones Nitriles (cyano compounds) Sulfides Thiols... [Pg.466]

Application of the Beckmann cleavage route to the preparation of 18-norandrostan-17-ones185 (219) has been improved by intermediate formation of the 13-carboxy-13,17-seco-nitriles (217), which cyclized with base to form the 13a- and 13/3-isomers of the a-cyano-ketone (218) and thence the 18-nor-13a- and -13/3-androstan-17-ones (219).186 A similar reaction sequence has been employed for... [Pg.255]

The formation of cyano ketones by this method is illustrated by the conversion of phenacyl halides to the corresponding nitriles. Ring closure to cyclopropane derivatives is a side reaction which has been encountered with y-halo ketones. Benzalacetophenone dibromide is converted by alcoholic potassium cyanide to the fi-cyaao ketone, the a-halogen atom being reduced. Several a-chloro ketones have been found to yield a-cyano epoxides. ... [Pg.748]

Grignard reagents also add to conjugated substrates such as a,p-unsaturated ketones, cyano-ketones, °° esters, and nitriles, but 1,2-addition may seriously compete The product is often controlled by steric factors. Thus 145 with phe-... [Pg.1114]

B.iv. Nitrile Enolates. Nitrile enolates are formed by reaction of a nitrile with LDA or another suitable base. Both alkylation 30 and condensation reactions with aldehydes 3 or ketones are known. 32 in addition to alkyl halides and carbonyl derivatives, condensation can occur with another nitrile. The base-catalyzed condensation of two nitriles to give a cyano-ketone, via an intermediate cyano enolate, is known as the Thorpe reaction. 33.109e Reaction of butanenitrile with sodium ethoxide gave a nitrile enolate, which reacted with a second molecule of butanenitrile at the electrophilic cyano carbon to give 206. Hydrolysis gave an intermediate imine-nitrile (207), which is in equilibrium with the enamine form (208, sec. 9.6.A). Hydrolysis led to the final product of the Thorpe reaction, an a-cyano ketone, 209. 33 Mixed condensations are possible when LDA and kinetic conditions are used to generate the a-lithionitrile (a mixed Thorpe reaction). When pentanenitrile was treated with LDA and condensed with benzonitrile, 2-cyano-l-phenyl-1-pentanone was the isolated product after acid hydrolysis. Nitrile enolates can also be alkylated with a variety of alkyl halides. 34... [Pg.752]

Thus, in the presence of a strong base, nitriles of the type RCH2CN will lose a proton and undergo a reaction analogous to an aldol condensation in which a carbanion will attack the electropositive carbon of the cyano group, There is a proton transfer to yield another stable carbanion which is hydrolyzed in acid media to the a-cyano-ketone. [Pg.873]

Shono and coworkers achieved electroreductive intra- and intermolecular couplings of ketones and nitriles in 2-propanol solutions containing Et4NTos using Sn cathodes at controlled potential (-2.8 V SCE). Intramolecular coupling of cyclic y- and (5-cyano ketones, besides good to excellent yields, proved to be cis stereoselective when a-hydroxy ketones with bicyclo[3.3.0] or [4.3.0] skeletons were formed. When the reactions were carried out at 65 °C instead of 25 °C, dehydration of hydroxy ketones occurred and the corresponding a,jS-unsaturated ketones were obtained. The presence of alkyl or 2-ethoxycarbonyl substituents did not hinder the cyclization. In Table 13 some representative examples are shown. [Pg.611]

The decarbalkoxylation of malonate esters, (3-keto esters, oc-cyano esters and oc-sulfonyl esters in dipolar aprotic solvents, at high temperatures, in the presence of water and/or salt, to yield esters, ketones, nitriles and sulfonyl derivatives, respectively ... [Pg.347]

This chapter explores several different carbon-carbon bond-forming reactions that lead to a variety of functionalized molecules diketones, hydroxy-ketones and hydroxy-aldehydes, keto-esters, keto-aldehydes, keto-nitriles, cyano-esters, hydroxy-nitriles, and cyano-aldehydes and cyano-ketones. The reactions that form these products may be categorized by defining the relevant disconnection. [Pg.1161]

Amine, Alcohol, Aldehyde, Alkane, Alkene, Alkyl Halide, Alkyne, Carboxylic Acid, Epoxide, Ether, Ketone, Nitrile (cyano), Nitro, Phenyl Group (benzene ring) and Thiol. [Pg.252]

Szantay and coworkers were able to improve the efficiency of the yohimbine synthetic sequence by utilizing the nitrile 265, derived from the ketone 260 (Scheme 3.42) (48,49). Dieckmann cyclization of 265 afforded regioselec-tively the a-cyano ketone 267 which on treatment with sodium borohydride provided the epimeric j5-cyano alcohols 268, 269, and 270. Nitriles 268 and 269 were then independently converted to yohimbine (4) and ) -yohimbine (5), respectively. [Pg.249]

As a class of compounds, nitriles have broad commercial utility that includes their use as solvents, feedstocks, pharmaceuticals, catalysts, and pesticides. The versatile reactivity of organonitnles arises both from the reactivity of the C=N bond, and from the abiHty of the cyano substituent to activate adjacent bonds, especially C—H bonds. Nitriles can be used to prepare amines, amides, amidines, carboxyHc acids and esters, aldehydes, ketones, large-ring cycHc ketones, imines, heterocycles, orthoesters, and other compounds. Some of the more common transformations involve hydrolysis or alcoholysis to produce amides, acids and esters, and hydrogenation to produce amines, which are intermediates for the production of polyurethanes and polyamides. An extensive review on hydrogenation of nitriles has been recendy pubHshed (10). [Pg.217]

Reactions. The chemical properties of cyanoacetates ate quite similar to those of the malonates. The carbonyl activity of the ester function is increased by the cyano group s tendency to withdraw electrons. Therefore, amidation with ammonia [7664-41-7] to cyanoacetamide [107-91-5] (55) or with urea to cyanoacetylurea [448-98-2] (56) proceeds very easily. An interesting reaction of cyanoacetic acid is the Knoevenagel condensation with aldehydes followed by decarboxylation which leads to substituted acrylonitriles (57) such as (29), or with ketones followed by decarboxylation with a shift of the double bond to give P,y-unsaturated nitriles (58) such as (30) when cyclohexanone [108-94-1] is used. [Pg.470]

An unusual method for the preparation of syndiotactic polybutadiene was reported by The Goodyear Tire Rubber Co. (43) a preformed cobalt-type catalyst prepared under anhydrous conditions was found to polymerize 1,3-butadiene in an emulsion-type recipe to give syndiotactic polybutadienes of various melting points (120—190°C). These polymers were characterized by infrared spectroscopy and nuclear magnetic resonance (44—46). Both the Ube Industries catalyst mentioned previously and the Goodyear catalyst were further modified to control the molecular weight and melting point of syndio-polybutadiene by the addition of various modifiers such as alcohols, nitriles, aldehydes, ketones, ethers, and cyano compounds. [Pg.531]

Carboxyl-related and acyl substituents. Included here are cyano, protonated amidinium ion, thionoacyl, acyl (Ar—CO, H—CO, Alkyl—CO), carboxamido, carboaryloxy, carboalkoxy, carboxy (unionized), amidino (unionized), and carboxylate anion, listed approximately in order of decreasing electron attraction or activation. The relative activation by some of these groups (e.g., ketone, aldehyde, nitrile) will change upon reversible interaction with the nucleophile, which will vary with the group and with the nucleophile (e.g., MeO , N3, NCS ). Irreversible interaction will be obvious when the reaction products in kinetic studies are characterized. [Pg.228]


See other pages where Cyano-ketones => nitriles is mentioned: [Pg.99]    [Pg.1239]    [Pg.197]    [Pg.267]    [Pg.270]    [Pg.62]    [Pg.771]    [Pg.964]    [Pg.771]    [Pg.47]    [Pg.1388]    [Pg.771]    [Pg.240]    [Pg.252]    [Pg.302]    [Pg.240]    [Pg.197]    [Pg.242]    [Pg.433]    [Pg.84]    [Pg.313]    [Pg.81]    [Pg.202]    [Pg.5]    [Pg.178]    [Pg.126]    [Pg.785]    [Pg.157]    [Pg.786]    [Pg.246]   
See also in sourсe #XX -- [ Pg.752 ]




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Cyano ketones

Cyano ketones, from nitriles

Nitriles cyano

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