2- cyano-l,3-butadiene

The readily available diethyl 2-cyano-2-(trimethylsilyl)ethylphosphonate appears to be an attractive reagent for the synthesis of 2-cyano-l,3-butadienes. Their formation combines the Peterson and Homer-Wadsworth-Emmons reactions in a one-pot process. The reaction has been developed with a variety of aldehydes, and the yields are generally high (34-89%, Scheme 2.38). ... 

Nakano, M., and Okamoto, Y, A convenient synthesis of 2-cyano-l,3-butadienes by the reaction of diethyl 2-cyano-2-trimethylsilylethanephosphonate with carbonyl compounds. Synthesis, 917, 1983. 

Diethyl 2-cyano-2-(trimethylsilyl)ethylphosphonate smoothly reacts with carbonyl compounds under basic conditions (LDA) to provide 2-cyano-2-aIkenylphosphonates by a Peterson reaction. Subsequent Homer-Wadsworth-Emmons reaction affords substituted 2-cyano-l,3-butadienes in moderate to good yields (34-89%) by treatment with LDA and then with a second equivalent of carbonyl compound (Scheme 6.29). ... 

Janecki, T., A convenient synthesis of substituted 2-cyano-l,3-butadienes, Synthesis. 167, 1991. Ting, P.C., and Solomon, D.M., Synthesis of spiro[4, 5, 10,11-tetrahydro-5//-dibenzo[a,d]cyclohep-ten-5-yl-2 (37/)-furans] as potential cytokine inhibitors, J. Heterocycl. Chem., 32, 1027, 1995. Armesto, D., flail ego, M.G., Horspool, W.M., and Agarrabeitia, A.R., A new photochemical synthesis of cyclopropanecarboxylic acids present in pyrethroids by the aza-di-Jt-methane reanangement. Tetrahedron, 51, 9223, 1995. 

Production and Properties of 2-Cyano-l,3-butadiene Homo- and Copolymers... 

Electron-withdrawing or electron-donor substituent in 2 and/or 3 position of acyclic dienes directs the reactions to proceed through both concerted and non-concerted processes. For example, 2-cyano-l,3-butadiene 11 gives 12 and 13 [20]. 

Cycloadditions to a cyano group are comparatively rare. The high-temperature reactions of 1,3-dienes, e.g. butadiene, isoprene and 2-chloro-l,3-butadiene, with dicyanogen, propionitrile or benzonitrile result in formation of pyridines (equation 80)70. Sulfonyl cyanides 147, obtained by the action of cyanogen chloride on sodium salts of sulfinic acids, add to dienes to give dihydropyridines 148, which are transformed into pyridines 149 by oxidation (equation 81)71. 

The decrease of electron density necessary for inverse electron demand aza Diels-Alder reactions can also be effected by appropiate substituents attached to C-2, especially by a cyano moiety. Several l-aza-2-cyano-1,3-butadienes have been investigated by Fowler and his coworkers in this context [243-245]. Strikingly, the easily accessable 1-aza-l,3-butadiene 3-29 undergoes cycloaddition not only with electron-rich dienophiles, it reacts as well with neutral and even with electron-deficient dienophiles (Fig. 3-10) [246,247],... 

The expressions are an outcome of the terminal model theory with several steady-state assumptions related to free-radical fiux (14,23). Based on copolymerization studies and reactivity ratios, chloroprene monomer is much more reactive than most vinyl and diene monomers (Table 1). 2,3-Dichloro-l,3-butadiene is the only commercially important monomer that is competitive with chloroprene in the free-radical copolymerization rate. 2,3-Dichlorobutadiene or ACR is used commercially to give crystallization resistance to the finished raw polymer or polymer vulcanizates. a-Cyanoprene (1-cyano-l,3-butadiene) and /3-cyanoprene (2-cyano-1,3-butadiene) are also effective in copolymerization with chloroprene but are difficult to manage safely on a commercial scale. Acrylonitrile and methacrylic acid comonomers have been used in limited commercial quantities. Chloroprene-isoprene and chloroprene-styrene copolymers were marketed in low volumes during the 1950s and 1960s. Methyl methacrylate has been utilized in graft polymerization particularly for vinyl adhesive applications. A myriad of other comonomers have been studied in chloroprene copolymerizations but those copolymers have not been used with much commercial success. 

Substituierte Butadiene, wie l-Cyano-l,3-butadien, ergeben neben anderen hydrodimeren Produkten als Hauptmenge l,8-Dicyano-2,6-octadien. Bei der Reduktion der Butadiene wird wegen der Konju-... 

Ethyl frfl/is-l,3-butadiene-l-carbamate, 59, 5 Ethyl butyrylacetate, 55, 73, 75 Ethyl carbamate, 57, 95 Ethyl chloroformate, 59, 2 Ethyl cyanoacetate, 55, 58, 60 57,80 ETHYL 1-CYANO-l-METHYLCYCLO-HEXANECARBOXYLATE, 55, 57 Ethyl 7-2-cyano-6-octenoate, 55,57 Ethyl cyano(pentafluorophenyl)acetate,... 

Copper(II) l,3-di(5-tetrazolyl)triazenide, 1429 5-Cyano-4-diazo-4//-l,2,3-triazole, 1345 Cyanoguanidine, 0813 Cyanohydrazonoacetyl azide, 1083 2,3-Diazido-l,3-butadiene, 1437 1,2-Diazidocarbonylhydrazine, 0720 Diazidomethy leneazine, 1021... 

Ab initio and density functional theoretical studies of the 4 + 2-cycloaddition of 2-azabutadiene with formaldehyde predict a concerted reaction that agrees well with experimental evidence.184 The azadiene A-plienyl-l-aza-2-cyanobuta-l,3-diene reacts with electron-rich, electron-poor, and neutral dipolarophiles under mild thermal conditions.185 5,6-Diliydro-4//-1,2-oxazines have been shown to be usefiil as synthon equivalents of 2-cyano-l-azabuta-1,3-dienes.186 The intramolecular Diels-Alder reaction of 1-aza-l,3-butadienes (106) can be activated by a 2-cyano substituent (Scheme 37).187 Stereoselectivity in the hetero-Diels-Alder reactions of heterobutadienes, nitrosoalkenes, and heterodienophiles has been extensively reviewed.188 The azadiene l-(f-butyldimethylsilyloxy)-l-azabuta-1,3 -diene (107) reacts with halobenzo-quinones, naphthoquinones, and A-phcnylmalcimidc to yield low to good yields of various pyridine heterocycles (108) (Scheme 38).189 The 4 + 2-cycloaddition of homophthalic anhydride with A-(cinnamylidcnc)tritylaminc produces the 3,4-adduct whereas with A -(cinnamylidcnc)bcnzylidinc the 1,2-adduct is produced.190... 

The Diels-Alder reaction of 2,3-dimethyl-l,3-butadiene and a-iminotrifluoropropionitrile gives 3,4-dimethyl-6-cyano-6-trifluoro-methyl-3-piperideine (44) in 80% yield.37... 

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