Enones malononitrile

A weak base such as glycine added to [HMIMjPFg has also been reported to catalyze a Knoevenagel reaction of malononitrile and benzaldehyde 110). A KOH-treated [BMIMjPFg also provides a suitable medium for the Corey-Chaykovsky epoxidation of enones and cyclopropanation of aldehydes using trimethyl sulfonium iodide (///). 

To complete the section on the synthesis of 4,4 -bipyridines, we summarize the methods reported for the preparation of some substituted 4,4 -bi-pyridines and 4,4 -bipyridinones. These methods are closely analogous to syntheses already discussed for some of the isomeric bipyridines. Thus the Hantzsch reaction using pyridine-4-aldehyde, ethyl acetoacetate, and ammonia gives 3,5-di(ethoxycarbonyl)-1,4-dihydro-2,6-dimethyl-4,4 -bipyridine, which after oxidation, followed by hydrolysis and decarboxylation, afforded 2,6-dimethyl-4,4 -bipyridine. Several related condensations have been reported. Similarly, pyridine-4-aldehyde and excess acetophenone gave l,5-diphenyl-3-(4-pyridyl)pentane-l,5-dione, which with ammonium acetate afforded 2,6-diphenyl-4,4 -bipyridine. Alternatively, 1-phenyl-3-(4-pyridyl)prop-2-enone, A-phenacylpyridinium bromide, and ammonium acetate gave the same diphenyl-4,4 -bipyridine, and extensions of this synthesis have been discribed. Condensation of pyridine-4-aldehyde with malononitrile in the presence of an alcohol and alkaline catalyst produced compounds such as whereas condensations of... 

Ni(II)(OAc)2bpy and Co(II)(OAc)2bpy catalyze the Michael addition of nitro-methane, malononitrile, and aniline to a,j8-unsaturated ketones, methyl acrylate, and acrylonitrile in DMF under neutral conditions [116]. FeCls 6H2O is a highly efficient catalyst of Michael reaction of 1,3-dicarbonyl compounds with a,/3-unsaturated ketones under mild and neutral conditions (Sch. 24) [117]. There is literature precedent for this reaction with dual catalysis Ni(II) immobilized on a clay support and FeCl3 to activate the enone [118]. The mechanism proposed for the single-center catalysis involves coordination of the enone to a diketonato complex [119]. The chemo-... 

Dithiins are produced by the reactions of geminal dithiols with enones such as chalcone and benzylidene acetophenone (Equation (54)) <62JOC4488, 66BSF1920>. Treatment of geminal dithiols with malononitrile also gives rise to 1,3-dithiins (Equation (55)) <62JPR2ll>. 

There is little doubt that the addition of acrylonitrile and related compounds to a variety of substrates provides a useful synthetic path for the formation of many bicyclic compounds. Typical of this is the photoaddition of malononitrile or fumaronitrile to 3-methylcyclohex-2-enone which provides four adducts in a ratio of 29 15 21 35. The structure of the predominant isomer was determined by X-ray crystallography and was established to be the cyclobutane 279. The ratio of the products obtained from these experiments was shown to be independent of the dose of irradiation. Quantum yield... 

Photolysis of 2-amino-4//-pyrans, readily obtained from malononitrile and enones, offers a useful route to substituted cyclobutenes <97JCS(P1)3401>. 

Scheme 4.31 Enantioselective Michael addition of malononitrile and cyanosulfones to enones.

In 2010, Jorgensen et al. developed an enantioselective tandem reaction of propargylated malononitriles with cyclic enones sequentially catalysed by a cinchona alkaloid-derived primary amine catalyst in the presence of (J )-mandelic acid as an additive for the first Michael step, and a gold catalyst for the second tandem exo-dig cyclisation-isomerisation reaction. " As shown in Scheme 7.62, the corresponding chiral bicyclic enones were achieved in good yields and high enantioselectivities of up to 96% ee, albeit low to moderate diastereoselectivities (34-66% de). 

When malononitrile is reacted with allenes in the presence of palladium catalysts, insertion into the C-H bond is observed with formation of a linear adduct Also, phosphine catalysts are used in an asymmetric [3+2] cycloaddition of carbo-ethoxyallene 302 with enones to give the isomeric cycloadducts 303 and 304 in 54-87 % yield (% ee in 303, the major product, 87-89. ... 

In the second reaction, a Michael-Michael cascade between an unsaturated oxin-doles 17 and enones 22 was shown to be catalyzed by a primary amine-derived catalyst (II) (Scheme 10.3). The reaction afforded the spirooxindoles 23 in excellent yields and diastereo and enantioselectivities. Wang used a similar approach in the reaction of isatylidene malononitriles and enones [12]. The reaction was catalyzed by the dual combination of cinchona-based chiral primary amine and BINOL phosphoric acids to afford the spirocycles in excellent yields (88-99%), diastereo (up to 99 1 dr), and enantioselectivities (95-99% ee). 

Eucarvone undergoes ring contraction to the related bicyclic product (279) and malononitrile on treatment with tetracyanoethylene in chloroform-trifluoroacetic acid, possibly via (280). Alkylation of eucarvone also gives largely a ring-contracted product, the enone (281). ... 

Recently, other research groups have developed the addition of 1,3 dicarbonyl or related compounds to enones. For example, Lattanzi reported the addition of malononitriles to enones catalyzed by cinchona alkaloids with good yields and enantioselectivities [84], Jaszay reported the addition of diethylcyanomethyl phos-phonate to enones using thiourea catalysts with moderate yields and enantioselectivities [85], and Wang reported the Michael addition of ketones to chalcones using pyrroUdine-derived catalysts with good yields and excellent enantioselectivities [86]. 

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