7443-52-9Relevant articles and documents
Transformation of organic compounds in the presence of metal complexes. IV. Hydrosilylation of 2- and 4-alkylcyclohexanones on rhodium(I) complexes
Felfoeldi, K.,Kapocsi, I.,Bartok, M.
, p. 411 - 416 (1989)
The hydrosilylation of 2- and 4-alkylcyclohexanones with Ph2SiH2 was studied under various conditions.The isomeric distribution of the resulting alcohols, i.e. the stereochemistry of the hydrosilylation, is influenced by the position and size of the alkyl groups, the catalyst concentration, the reaction temperature, and the types of ligand attached.
Potassium Triphenylborohydride. A New Reducting Agent for the Reduction of Carbonyl Compounds with an Exceptional Stereo- and Chemoselectivity
Yoon, Nung Min,Kim, Kwan Eung,Kang, Jahyo
, p. 226 - 229 (1986)
Potassium triphenylborohydride (KTPBH), a highly hindered potassium triarylborohydride prepared from triphenylborane and potassium hydride, exhibits remarkable stereo- and chemoselectivity for the reduction of carbonyl compounds.KTPBH reduces 2-methylcyclohexanone to give cis-2-methylcyclohexanol with an excellent stereospecificity (98.5:1.5), approaching that of lithium tri-sec-butylborohydride.KTPBH also shows a remarkable chemoselectivity.It shows 97:3 selectivity between cyclohexanone and cyclopentanone and 99.4:0.6 selectivity between cyclohexanone and 4-heptanone.This chemoselectivity is comparable to those achieved by lithium di-n-butyl-9-BBN and tert-butylamine-borane, the best two reagents reported for such purposes.KTPBH is stable over 2 months at room temperature, and this reagent possesses a practical advantage in the isolation of the alcohol product without oxidation and distillation.
Addition Compounds of Alkali Metal Hydrides. 27. A General Method for Preparation of the Potassium 9-Alkoxy-9-boratabicyclononanes. A New Class of Stereoselective Reducing Agents
Brown, Herbert C.,Cha, Jin Soon,Nazer, Behrooz,Brown, Charles A.
, p. 549 - 553 (1985)
The reaction in tetrahydrofuran of potassium hydride with representative B-alkoxy-9-borabicyclononanes (B-OR-9-BBN) containing alkoxy groups with increasing steric requirements was examined in detail to establish the generality of this synthesis of the corresponding potassium 9-alkoxy-9-boratabicyclononanes (K9-OR-9-BBNH) and the stereoselectivities of these new reagents for the reduction of cyclic ketones.For R = Me and n-Bu, the reactions with potassium hydride are very fast, almost instantaneous, even at 0 deg C.However, the products are unstable and rapidly undergo redistribution, even in the presence of excess potassium hydride.Moderately hindered alkoxy derivatives, R = 2-Pr and 2-Bu, react somewhat slower (1 h at 0 deg C and 25 deg C, respectively) and the products are stable to redistribution.More hindered alkoxy derivatives, R = t-Bu, t-Am, Thx, require 24 h at 25 deg C.Even more hindered alkoxy groups, R = 3-ethyl-3-pentyl and 2,4-dimethyl-2-pentyl, require even longer reaction times and higher temperatures.All reagents show high stereoselectivities in the reduction of cyclic ketones, with the stereoselectivities generally increasing with increasing steric requirements of the alkoxy substituent.The thexyl derivative appears especially favorable, with the byproducts of the reaction readily removed from the reaction mixture.
Epoxide opening with organocuprates and grignard reagents in the presence of chiral ligands
Davies, Stephen G.,Wollowitz, Susan
, p. 4175 - 4178 (1980)
The reaction of cyclohexene oxide with organocuprates and Grignard reagents in the presence of chiral ligands to give chiral β-substituted alcohols in low optical yields is described.
Addition Compounds of Alkali Metal Hydrides. 28. Preparation of Potassium Dialkoxymonoalkylborohydrides from Cyclic Boronic Esters. A New Class of Reducing Agents
Brown, Herbert C.,Park, Won Suh,Cha, Jin Soon,Cho, Byung Tae,Brown, Charles A.
, p. 337 - 342 (1986)
The reaction of cyclic boronic esters possesing a wide range of steric requirements with excess potassium hydride to form the corresponding potassium dialkoxymonoalkylborohydrides was explored.In case involving a less hindered diol such as ethylene glycol, 2,3-butanediol, or 1,3-propanediol, the reaction is slightly exothermic and quite facile, being complete in less than 1 h at 25 deg C.In the case involving a highly hindered diol such as pinacol, the reaction is very sluggish, even at 65 deg C.The stability of the potassium dialkoxymonoalkylborohydrides is strongly dependent upon the steric bulkiness of the alkyl groups of the boronic ester.Thus, for R = n-hexyl, 3-hexyl, tert-butyl, or thexyl, the addition product is quite stable to disproportionation.However, for R = methyl, the corresponding borohydride is unstable, undergoing rapid redistribution to form a white precipitate.The stable potassium dialkoxymonoalkylborohydrides thus formed reduce 2-methylcyclohexanone with moderate stereoselectivity, giving the cis isomer preferentially, with selectivities of 73-84percent
Cobalt-Nanoparticles Catalyzed Efficient and Selective Hydrogenation of Aromatic Hydrocarbons
Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Alshammari, Ahmad S.,Altamimi, Rashid M.,Kreyenschulte, Carsten,Pohl, Marga-Martina,Lund, Henrik,Jagadeesh, Rajenahally V.,Beller, Matthias
, p. 8581 - 8591 (2019/09/12)
The development of inexpensive and practical catalysts for arene hydrogenations is key for future valorizations of this general feedstock. Here, we report the development of cobalt nanoparticles supported on silica as selective and general catalysts for such reactions. The specific nanoparticles were prepared by assembling cobalt-pyromellitic acid-piperazine coordination polymer on commercial silica and subsequent pyrolysis. Applying the optimal nanocatalyst, industrial bulk, substituted, and functionalized arenes as well as polycyclic aromatic hydrocarbons are selectively hydrogenated to obtain cyclohexane-based compounds under industrially viable and scalable conditions. The applicability of this hydrogenation methodology is presented for the storage of H2 in liquid organic hydrogen carriers.
Demystifying Cp2Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp2TiCl
Gordon, Jonathan,Hildebrandt, Sven,Dewese, Kendra R.,Klare, Sven,Gans?uer, Andreas,Rajanbabu,Nugent, William A.
supporting information, p. 4801 - 4809 (2019/01/08)
The role of Cp2Ti(H)Cl in the reactions of Cp2TiCl with trisubstituted epoxides has been investigated in a combined experimental and computational study. Although Cp2Ti(H)Cl has generally been regarded as a robust species, its decomposition to Cp2TiCl and molecular hydrogen was found to be exothermic (ΔG = -11 kcal/mol when the effects of THF solvation are considered). In laboratory studies, Cp2Ti(H)Cl was generated using the reaction of 1,2-epoxy-1-methylcyclohexane with Cp2TiCl as a model. Rapid evolution of hydrogen gas was demonstrated, indicating that Cp2Ti(H)Cl is indeed a thermally unstable molecule, which undergoes intermolecular reductive elimination of hydrogen under the reaction conditions. The stoichiometry of the reaction (Cp2TiCl:epoxide = 1:1) and the quantity of hydrogen produced (1 mol per 2 mol of epoxide) is consistent with this assertion. The diminished yield of allylic alcohol from these reactions under the conditions of protic versus aprotic catalysis can be understood in terms of the predominant titanium(III) present in solution. Under the conditions of protic catalysis, Cp2TiCl complexes with collidine hydrochloride and the titanium(III) center is less available for "cross-disproportionation" with carbon-centered radicals; this leads to byproducts from radical capture by hydrogen atom transfer, resulting in a saturated alcohol.
Mild and Regioselective Hydroxylation of Methyl Group in Neocuproine: Approach to an N,O-Ligated Cu6 Cage Phenylsilsesquioxane
Bilyachenko, Alexey N.,Levitsky, Mikhail M.,Khrustalev, Victor N.,Zubavichus, Yan V.,Shul'Pina, Lidia S.,Shubina, Elena S.,Shul'Pin, Georgiy B.
supporting information, p. 168 - 171 (2018/02/06)
The self-Assembly synthesis of Cu(II)-silsesquioxane involving 2,9-dimethyl-1,10-phenanthroline (neocuproine) as an additional N ligand at copper atoms was performed. The reaction revealed an unprecedented aerobic hydroxylation of only one of the two methyl groups in neocuproine to afford the corresponding geminal diol. The produced derivative of oxidized neocuproine acts as a two-centered N,O ligand in the assembly of the hexacopper cage product [Cu6(Ph5Si5O10)2·(C14H11N2O2)2] (1), coordinating two of the six copper centers in the product. Two siloxanolate ligands [PhSi(O)O]5 in the cis configuration coordinate to the rest of the copper(II) ions. Compound 1 is a highly efficient homogeneous precatalyst in the oxidation of alkanes and alcohols with peroxides.
Heptanuclear Fe5Cu2-Phenylgermsesquioxane containing 2,2′-Bipyridine: Synthesis, Structure, and Catalytic Activity in Oxidation of C-H Compounds
Bilyachenko, Alexey N.,Khrustalev, Victor N.,Zubavichus, Yan V.,Shul'Pina, Lidia S.,Kulakova, Alena N.,Bantreil, Xavier,Lamaty, Frédéric,Levitsky, Mikhail M.,Gutsul, Evgeniy I.,Shubina, Elena S.,Shul'Pin, Georgiy B.
, p. 528 - 534 (2018/01/11)
A new representative of an unusual family of metallagermaniumsesquioxanes, namely the heterometallic cagelike phenylgermsesquioxane (PhGeO2)12Cu2Fe5(O)OH(PhGe)2O5(bipy)2 (2), was synthesized and structurally characterized. Fe(III) ions of the complex are coordinated by oxa ligands: (i) cyclic (PhGeO2)12 and acyclic (Ph2Ge2O5) germoxanolates and (ii) O2- and (iii) HO- moieties. In turn, Cu(II) ions are coordinated by both oxa (germoxanolates) and aza ligands (2,2′-bipyridines). This "hetero-type" of ligation gives in sum an attractive pagoda-like molecular architecture of the complex 2. Product 2 showed a high catalytic activity in the oxidation of alkanes to the corresponding alkyl hydroperoxides (in yields up to 30%) and alcohols (in yields up to 100%) and in the oxidative formation of benzamides from alcohols (catalyst loading down to 0.4 mol % in Cu/Fe).
(Poly)cationic λ3-Iodane-Mediated Oxidative Ring Expansion of Secondary Alcohols
Walters, Jennifer C.,Tierno, Anthony F.,Dubin, Aimee H.,Wengryniuk, Sarah E.
supporting information, p. 1460 - 1464 (2018/04/06)
Herein, a simplified approach to the synthesis of medium-ring ethers through the electrophilic activation of secondary alcohols with (poly)cationic λ3-iodanes (N-HVIs) is reported. Excellent levels of selectivity are achieved for C–O bond migration over established α-elimination pathways, enabled by the unique reactivity of a novel 2-OMe-pyridine-ligated N-HVI. The resulting hexafluoroisopropanol (HFIP) acetals are readily derivatized with a range of nucleophiles, providing a versatile functional handle for subsequent manipulations. The utility of this methodology for late-stage natural product derivatization was also demonstrated, providing a new tool for diversity-oriented synthesis and complexity-to-diversity (CTD) efforts. Preliminary mechanistic investigations reveal a strong effect of alcohol conformation on the reactive pathway, thus providing a predictive power in the application of this approach to complex molecule synthesis.
