Piperidines 2,6-dicyano

Dicyano-2,4,8-triphenyl-7-phenylsulfonyl-6/f-pyrido[], 2-a]pyrimi-dine-6-thione was obtained in the reaction of 6-amino-1-benzoyl-5-cyano-4-phenyl-3-phenylsulfonylpyridin-2(]//)-one and benzylidenemalononitrile in the presence of piperidine in boiling dioxane for 4h in 59% yields (98M1049). 

Valethamate bromide dl-1 -Benzyl-4-(1,3-dicyano-1 -phenyl-propyl)piperidine HCI Dexetimide Benzylethanolamine Phenmetrazine... 

Cyclization also occurs extensively with glutaronitriles. In hydrogenation of 1,3-dicyano-2-propanol with Raney Ni, the formation of 4-hydroxypiperidine predominated over the formation of l,5-diamino-3-propanol even in the presence of liquid ammonia.114 Hydrogenation in the absence of ammonia further increased the yield of the piperidine (eq. 7.62). Adiponitrile was transformed to azacycloheptane in high selectivity in the hydrogenation over y-Al203-supported Ni catalysts in a continuous process at 170°C and 0.1 MPa H2 in the absence of ammonia.115... 

With adiponitrile, an open-chain dinitrile, however, such cyclization leading to a seven-membered cyclic imine occurs to a much lesser extent (see, e.g., eq. 7.25). The hydrogenative cyclizations have been utilized for the synthesis of pyrrolidine and piperidine derivatives from 1,2- and 1,3-dicyano compounds.118,119... 

Detailed H NMR and EPR spectroscopic studies performed in DMSO solution demonstrated that the autoreduction of tetraphenylporphinatoiron(III) chloride in the presence of piperidine or potassium cyanide leads to the formation of the corresponding six-coordinate, diamagnetic dicyano or bis(piperidine) Fe complexes, [TPPFe (CN)2] or [TPPFe (Pip)2], which are identified by their characteristic pyrrole-H shifts at 8.8-9.0 ppm. In addition to the Fe complexes, a cyanide or a piperidine radical is formed. 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

Multicomponent reactions continue to be a popular way to achieve rapid construction of polysubstituted pyrrole skeletons. Cyanopyrrole 59 was synthesized in moderate to good yields from gem-dicyano olefin 56, piperidine (57), and tert-butyl isocyanide (58) without the need for a catalyst. Although the reaction is limited to cyanopyrroles, the nitrile moiety is a useful handle for further chemical transformations (130L4246). 

Among all the pyridine derivatives, 2-amino-3,5-dicyano-6-sulfanyl pyridines are even more interesting because of their potential therapeutic applications. In synthetic chemistry, the cyclocondensation of aldehydes, malononitrile, and thiols is the most straightforward pathway. In general, this transformation can be realized under basic conditions. The bases reported included EtsN, DABCO, piperidine, morpholine, thiomorpholine, pyrrolidine, N,N-DIPEA, pyridine, 2,4,6-collidine, DMAP, aniline, iV-methylaniline, A,A-dimethylaniline and N,N-diethylaniline. Reactions under neutral conditions have been explored as well. In these cases, Cul nanoparticles [75], ZnCl2 [76], and nanocrystalline magnesium oxide [77] have been applied as the catalysts. 

Piperidine added dropwise with shaking to a methanolic soln. of 2-cyano-3-ethylcinnamonitrile and benzylidenemalononitrile, the product isolated after 6 hrs. -> 2,6-dicyano-4-methyl-3,5-diphenylaniline. Y 94%, F. e., also with isolation of intermediates, s. K. Gewald and W. Sdiill, J. pr. 313, 678 (1971),... 

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