19120-38-8Relevant academic research and scientific papers
Nickel(II)-carbene intermediates in reactions of geminal dihaloalkanes with nickel(0) reagents and the corresponding carbene capture as the phosphonium ylide
Eisch, John J.,Qian, Yun,Rheingold, Arnold L.
, p. 1576 - 1584 (2007)
In a previous study of geminal bond cleavages of substrates of the type R2CE2 [E2 = X2, O, S, Li(SO 2Ph)] by nickel(0) reagents [LnNi, Ln = (Cod)2, (Et4P)4], leading to R 2C=CR2 as products, the tentative hypothesis had been proposed that such reactions likely proceed via nickel(0)-carbene intermediates (J. J. Eisch, Y. Qian, M. Singh, J. Organomet. Chem. 1996, 512, 207). Because such proposed nickel(0)-carbenes do not satisfactorily account for reactions encountered with such α-eliminations, a detailed reexamination of the reaction of these nickel(0) reagents with geminal dihalides has been undertaken. For example, two reactions of such presumed nickel(0)-carbenes remained anomalous: (1) the failure of 5,5-dibromotetraphenylcyclopentadiene to form its expected dimer, octaphenylphenylfulvalene and instead the formation of triethylphosphonium tetraphenylcyclopentadienide in its reaction with (Et 3P)4Ni; and (2) the presumed capture of intermediate R2C=Ni0 in presence of the trapping agent (benzaldehyde or benzophenone). As to the first anomaly, a detailed study has shown that no trace of octaphenylfulvalene was formed. As to the second anomaly, the R 2C fragment could be trapped by the carbonyl reagents only in reactions involving (Et3P)4Ni, but not in reactions with (Cod)2Ni. This finding compels one to conclude that the carbonyl reagent is capturing the Wittig reagent, R2C=PEt3, and not R2C=Ni0. Based upon all present data, the mechanism of such C=C bond dimerizations is best explicable in terms of nickel(II)-carbenes. The triethylphosphonium tetraphenylcyclopentadienide formed here has by single-crystal X-ray structure determination, complemented by 13C NMR spectroscopic data, been found to have the zwitterionic structure Ph 4Cp--+PEt3 as its paramount resonance contributor. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Cyclopropane-alkene metathesis by gold(i)-catalyzed decarbenation of persistent cyclopropanes
Mato, Mauro,Martín-Torres, Inmaculada,Herlé, Bart,Echavarren, Antonio M.
, p. 4216 - 4219 (2019/05/06)
A gold(i)-catalyzed cyclopropane-alkene metathesis has been demonstrated with two new families of cyclopropane derivatives of naphthalene and phenanthrene (benzo-fused norcaradienes). In this process, metal carbene units are transferred from a persistent
Gold(I) Carbenoids: On-Demand Access to Gold(I) Carbenes in Solution
Sarria Toro, Juan M.,García-Morales, Cristina,Raducan, Mihai,Smirnova, Ekaterina S.,Echavarren, Antonio M.
supporting information, p. 1859 - 1863 (2017/02/05)
Chloromethylgold(I) complexes of phosphine, phosphite, and N-heterocyclic carbene ligands are easily synthesized by reaction of trimethylsilyldiazomethane with the corresponding gold chloride precursors. Activation of these gold(I) carbenoids with a variety of chloride scavengers promotes reactivity typical of metallocarbenes in solution, namely homocoupling to ethylene, olefin cyclopropanation, and Buchner ring expansion of benzene.
Silver-Catalyzed Cyclopropanation of Alkenes Using N-Nosylhydrazones as Diazo Surrogates
Liu, Zhaohong,Zhang, Xinyu,Zanoni, Giuseppe,Bi, Xihe
supporting information, p. 6646 - 6649 (2017/12/26)
An efficient silver-catalyzed [2 + 1] cyclopropanation of sterically hindered internal alkenes with diazo compounds in which room-temperature-decomposable N-nosylhydrazones are used as diazo surrogates is reported. The unexpected unique catalytic activity of silver was ascribed to its dual role as a Lewis acid activating alkene substrates and as a transition metal forming silver carbenoids. A wide range of internal alkenes, including challenging diarylethenes, were suitable for this protocol, thereby affording a variety of cyclopropanes with high efficiency in a stereoselective manner under mild conditions.
Cyclopropanation with gold(I) carbenes by retro-Buchner reaction from cycloheptatrienes
Solorio-Alvarado, César R.,Wang, Yahui,Echavarren, Antonio M.
, p. 11952 - 11955 (2011/10/04)
Cationic gold(I) promotes the retro-Buchner reaction of 7-substituted 1,3,5-cycloheptatrienes, leading to gold(I) carbenes that cyclopropanate alkenes.
Reactions of diazo compounds with alkenes catalysed by [RuCl(cod)(Cp)]: Effect of the substituents in the formation of cyclopropanation or metathesis products
Basato, Marino,Tubaro, Cristina,Biffis, Andrea,Bonato, Marco,Buscemi, Gabriella,Lighezzolo, Filippo,Lunardi, Pamela,Yianini, Chiara,Benetollo, Franco,Del Zotto, Alessandro
experimental part, p. 1516 - 1526 (2009/09/04)
The reaction of diazo compounds with alkenes catalysed by complex [RuCl(COd)(Cp)] (cod = 1, 5-cyclooctadiene, Cp = cyclopentadienyl) has been studied. The catalytic cycle involves in the first step the decomposition of the diazo derivative to afford the reactive [RuCl(Cp)I=C(R1)R 2)] intermediate and a mechanism is proposed for this step based on a kinetic study of the simple coupling reaction of ethyl diazoacetate. The evolution of the Ru-carbene intermediate in the presence of alkenes depends on the nature of the substituents at both the diazo N2=C(R 1)R2 (R1, R2 = Ph, H; Ph, CO 2Me; Ph, Ph; C(R1)R2 = fluorene) and the olefin substrates R3(H)C= C(H)R4 (R3, R4 = CO2Et, CO2Et; Ph, Ph; Ph, Me; Ph, H; Me, Br; Me, CN; Ph, CN; H, CN; CN, CN). A remarkable reactivity of the complex was recorded, especially towards unstable aryldiazo compounds and electron-poor olefins. The results obtained indicate that either cyclopropanation or metathesis products can be formed: the first products are favoured by the presence of a cyano substituent at the double bond and the second ones by a phenyl.
Formation of symmetrical alkenes by homocoupling of metallated sulfones under nickel catalysis
Gai, Yonghua,Julia, Marc,Jean-Noe,Verpeaux
, p. 805 - 816 (2007/10/03)
Summary -Allylic sulfones undergo a coupling reaction with organometallic compounds (Mg or Li) not only with copper catalysts but also with iron or nickel salts. With 7,7-disubstituted allylic sulfones and also saturated aliphatic sulfones, however, another reaction was observed whereby two molecules of the starting sulfone are coupled to give symmetrical alkenes. The scope of this reaction was investigated. Elsevier.
The reaction of benzotrihalides and benzal halides with magnesium. Synthetic and mechanistic studies
Ashby, E. C.,Al-Fekri, Dheya M.
, p. 275 - 292 (2007/10/02)
The benzotrihalides (PhCX3) where X = Cl, Br, and F were allowed to react with magnesium in THF at room temperature.When the halide was chloride or bromide, the trihalide gave diphenylacetylene in high yield in addition to several minor products which were identified.No reaction was observed when the halide was fluoride.When the corresponding dichloride was allowed to react with magnesium in THF, stilbene was formed as the major product.The possible mechanisms for these reactions are discussed.
Synthese d'olefines et de polyenes par doublement d'anions α-sulfonyles en presence de sels de nickel
Julia, Marc,Verpeaux, Jean-Noel
, p. 2457 - 2460 (2007/10/02)
The lithium or magnesium derivatives of allyl, benzyl and alkyl sulphones are converted efficiently by a catalytic amount of nickel(II) acetylacetonate into symmetrical olefins in THF at 60 deg C.Thus, phytoene was obtained in a 70percent yield from geranylgeranylsulphone.
Methods for the Construction of Linear 1,7-Diarylheptanoids; Synthesis of Di-O-methylcentrolobol and Precursors (Synthetic and Biosynthetic) to the meta,meta-Bridged Biphenyls Myricanol and Myricanone
Henley-Smith, Peter,Whiting, Donald A.,Wood, Andrew F.
, p. 614 - 622 (2007/10/02)
1,7-diarylheptanoids are a varied natural product class in which 'linear' types appear to be biosynthetic precursors to macro(carbo)cyclic (3), macro(oxa)cyclic (4), and condensed polycyclic (5) examples.Various methods (suitable for radiolabelling) are described for constructing 'linear' diarylheptanoids, including Grignard couplings (employing activated magnesium) with arylpropanals and oxazonium salts (11a), (11h), (15a), and (15b)> and dithian alkylation (15c)>.Alkyl-lithium treatment of the benzyloxydithian (19b) gave 1,2,3-triphenylcyclopropane.Syntheses via trialkylcyanoborates were frustrated by disproportionation of the intermediate trialkylboranes.The diarylheptanoids synthesised (11a-h) and (15a-e) include synthetic and biosynthetic precursors to meta,meta-bridged biphenyls and related macrocyclic ethers.
