22389-16-8Relevant academic research and scientific papers
Nickel-Catalyzed Cyclopropanation with NMe4OTf and nBuLi
Künzi, Stefan A.,Sarria Toro, Juan Manuel,Den Hartog, Tim,Chen, Peter
supporting information, p. 10670 - 10674 (2015/09/02)
Nickel was identified as a catalyst for the cyclopropanation of unactivated olefins by using in situ generated lithiomethyl trimethylammonium triflate as a methylene donor. A mechanistic hypothesis is proposed in which the generation of a reactive nickel carbene explains several interesting observations. Additionally, our findings shed light on a report by Franzen and Wittig published in 1960 that had been retracted later owing to irreproducibility, and provide a rational basis for the systematic development of the reaction for preparative purposes as an alternative to diazomethane or Simmons-Smith conditions.
Stereodirecting Effect of a Substrate Methoxy Substituent on the Addition of Singlet Methylene to a Double Bond
Young, Terry A.,O'Rourke, Colleen,Gray, Nathan B.,Lewis, Brian D.,Dvorak, Curt A.,et al.
, p. 6224 - 6228 (2007/10/02)
The stereodirecting effects of substrate methoxy, hydroxy, methylthio, and methyl substituents were examined in the addition of 1:CH2 to the double bonds of substrates 1a-d.The carbene, generated by photolysis of CH2N2, inserted into the C-H bonds of solvent and substrate, added to the substrate double bond to give products 2a-d, and attacked the oxygen or sulfur atom of substrates 1a-c to produce ylide intermediates which underwent 2,3-sigmatropic rearrangement to give products 3a-c.A preference for addition syn to the methoxy group of substrate 1a was observed when the reaction was run in pentane solution (syn-2a/anti-2a, 1.14 +/- 0.02), while a preference for formation of anti-2a was observed in diethyl ether solution (syn-2a/anti-2a, 0.92 +/- 0.03).A preference for 1:CH2 addition anti to the substrate substituent was observed for substrates 1b-d in both pentane and ether solution.The effect of the methoxy substituent was also examined in the addition of 1:CH2 to syn-7-methoxynorbornene (5b).Explanations for the substituent effects are offered based on both steric hindrance and interaction between 1:CH2 and the substituent, including formation and subsequent reaction of the ylide intermediates.
Interaction of diazoalkanes with unsaturated compounds. 12. Stereochemistry of cyclopropanation of norbornenes with diazomethane in the presence of transition metal complexes
Dzhemilev, U. M.,Dokichev, V. A.,Maidanova, I. O.,Nefedov, O. M.,Tomilov, Yu. V.
, p. 697 - 700 (2007/10/02)
The stereochemistry of cyclopropanation of norbornenes with diazomethane in the presence of Cu, Pd, and Rh compounds has been studied.Stereoselectivity of the cyclopropanation depends on the nature of the transition metal and does not depend on its valent state or ligand environment.The reaction proceeds predominantly as exo-cycloaddition of the methylene fragment.The greatest amount of endo-isomer (up to 47 percent) is formed in cyclopropanation of norbornadiene and exo-tricyclo2,4>oct-6-ene in the presence of Cu and Rh compounds.
Facile activation of zinc. Preparation of cyclobutanones via dichloroketene and cyclopropanes using the Simmons-Smith reaction
Stenstrom
, p. 2801 - 2810 (2007/10/02)
Zinc powder activated by heating in an inert atmosphere gave good yields when used for the title reactions. The very easy work up procedure for the cyclobutanones further increases the potential of the method.
Corner Attack on exo- and endo-Tricyclo2,4>octane by Deuteron and Mercuric Ions
Coxon, James M.,Steel, Peter J.,Whittington, Barry I.,Battiste, Merle A.
, p. 1383 - 1391 (2007/10/02)
Reaction of endo-tricyclo2,4>octane (1) with deuteron in methanol-d1 gave a mixture (62:38) of methoxy ethers 3b and 4b from cleavage of the most substituted cyclopropane bond.The reaction proceeds by attack of deuterium at the corner of the cyclopropane.Trapping of the intermediate cation 5b is competitive with rearrangement to the nonclassical cation 6b.Reaction of exo-tricyclo2,4>octane (2) under similar conditions gave methoxy ether 11b, which results from rupture of an external cyclopropyl bond, and methoxy ether 12b formed from rapture of the internal cyclopropyl bond with inversion at the site of both electrophilic and nucleophilic attack.Reaction of hydrocarbon 1 with mercuric acetate in methanol gave 4-endo-(acetoxymercurio)-2-endo-methoxybicyclooctane (3c) from attack of the mercuric ion at the corner of the cyclopropane and nucleophilic attack by methanol with inversion without molecular rearrangement.Similar reaction of the exo hydrocarbon 2 gave product 12c from internal bond rupture without molecular rearrangement and with inversion of configuration at the site of electrophilic and nucleophilic attack.In addition an almost equal quantity of 11c, a product of rupture of the external cyclopropyl bond, was formed.The stereochemistry of mercuric ion and deuteron attack at C2 at the corner of the cyclopropane ring of 1 and 2 is rationalized by consideration of the symmetry and energy of the molecular orbitals involved.
Competitive Cyclopropanation and Cross-metathesis Reactions of Alkenes Catalysed by Diruthenium Tatrakis Carboxylates
Noels, Alfred F.,Demonceau, Albert,Carlier, Eric,Hubert, Andre J.,Marquez-Silva, Rosa-Linda,Sanchez-Delgado, Roberto A.
, p. 783 - 784 (2007/10/02)
Addition of ethyl diazoacetate to a mixture of styrene and norbornene containing a catalytic amount of Ru2(OAc)4 promoted both the cyclopropanation and a selective cross-metathesis of the alkenes.
