50551-88-7Relevant academic research and scientific papers
Cooperative Mn(i)-complex catalyzed transfer hydrogenation of ketones and imines
Ganguli, Kasturi,Shee, Sujan,Panja, Dibyajyoti,Kundu, Sabuj
, p. 7358 - 7366 (2019/06/06)
The synthesis and reactivity of Mn(i) complexes bearing bifunctional ligands comprising both the amine N-H and benzimidazole fragments are reported. Among the various ligands, the N-((1H-benzimidazol-2-yl)methyl)aniline ligand containing Mn(i) complex presented higher reactivity in the transfer hydrogenation (TH) of ketones in 2-propanol. Experimentally, it was established that both the benzimidazole and amine N-H proton played a vital role in the enhancement of the catalytic activity. Utilizing this system a wide range of aldehydes and ketones were reduced efficiently. Notably, the TH of several imines, as well as chemoselective reduction of unsaturated ketones, was achieved in the presence of this catalyst. DFT calculations were carried out to understand the plausible reaction mechanism which disclosed that the transfer hydrogenation reaction followed a concerted outer-sphere mechanism.
Lewis Acid Mediated Cyclizations: Diastereoselective Synthesis of Six- to Eight-Membered Substituted Cyclic Ethers
Ghosh, Arun K.,Tomaine, Anthony J.,Cantwell, Kelsey E.
supporting information, p. 4229 - 4246 (2017/09/12)
Cyclic ethers are widely abundant in natural products. Cyclic ether templates are also utilized in drug design and medicinal chemistry. Although the synthetic processes for this class of compounds have been studied extensively with respect to five- and six-membered rings, medium-sized cyclic ethers are synthetically more challenging due to a variety of factors. Herein, we report our results on the Lewis acid catalyzed synthesis of medium-sized cyclic ethers in a diastereoselective manner..
6,6′-Dihydroxy terpyridine: A proton-responsive bifunctional ligand and its application in catalytic transfer hydrogenation of ketones
Moore, Cameron M.,Szymczak, Nathaniel K.
supporting information, p. 400 - 402 (2013/02/22)
The ligand 6,6′-dihydroxy terpyridine (dhtp) is presented as a bifunctional ligand capable of directing proton transfer events with metal-coordinated substrates. Solid-state analysis of a Ru(ii)-dhtp complex reveals directed hydrogen-bonding interactions of the hydroxyl groups of dhtp with a Ru-bound chloride ligand. The utility of dhtp was demonstrated by chemoselective transfer hydrogenation of ketones.
Ruthenium(II) trerdentate CNN complexes: Superlative catalysts for the hydrogen-transfer reduction of ketones by reversible insertion of a carbonyl group into the Ru-H bond
Baratta, Walter,Chelucci, Giorgio,Gladiali, Serafino,Siega, Katia,Toniutti, Micaela,Zanette, Matteo,Zangrando, Ennio,Rigo, Pierluigi
, p. 6214 - 6219 (2007/10/03)
(Chemical Equation Presented) Very low loading and short reaction times are characteristic features of the quantitative reduction of different ketones using 2-propanol and terdentate [RuX(CNN)-(dppb)] (X = H, Cl (see structure); dppb = Ph2P(CH2)4PPh2) complexes prepared from 6-(4′-methylphenyl)-2-pyridyl-methylamine. The reduction apparently takes place by reversible insertion of the substrate into the Ru-H bond, thus leading to a RuII alkoxide.
The photochemical nucleophile-olefin combination, aromatic substitution (photo-NOCAS) reaction. Part 10: intramolecular reactions involving alk-4-enols and 1,4-dicyanobenzene
McManus, Kimberly A.,Arnold, Donald R.
, p. 2158 - 2169 (2007/10/03)
Our study of the photochemical nucleophile-olefin combination, aromatic substitution (photo-NOCAS) reaction has been extended to include alk-4-enols.Irradiation of acetonitrile solutions of the alk-4-enols, 6-methyl-5-hepten-2-ol (16) and 5-methyl-5-hexen
Reactions of Some Cyclic Ethers in Superacids
Baig, Mirza Azam,Banthorpe, Derek V.,Carr, Graham,Whittaker, David
, p. 1981 - 1986 (2007/10/02)
The reactions of some epoxides and tetrahydrofuran derivatives in superacidic media have been studied.The tetrahydrofurans decompose only at 0 deg C or above, yielding, in some cases, unsaturated carbocations which react to give carbocyclic products, though many yield only tar.Cyclohexene oxides decompose more readily; unsubstituted, they slowly form an allylic ion; with one carbon at the epoxide link substituted they yield the ketone, and with both carbons substituted they give the ring-contracted aldehyde.Limonene 1,2-oxide behaves in a similar manner, though yielding small amounts of the ring-contracted protonated aldehyde (10).Reaction of geraniol 2,3-oxide is initially similar but the intermediate is intercepted intramolecularly to yield the hydroxy-iridoid ethers, 3,3,6β-trimethyl-cis-perhydrocyclopentafuran and 3,3,6α-trimethyl-cis-perhydrocyclopentafuran.Protonation of cyclohexene oxide or norbornene oxide yields onium salts, stable at -70 deg C, which show the addition to be either unsymmetrical (i.e. edge protonation) or to take place in two different positions.
Cyclic Ether Formation in Superacid Media
Carr, Graham,Whittaker, David
, p. 359 - 366 (2007/10/02)
The formation of ethers in superacids by interaction of a primary hydroxy group with a carbocation centre has been investigated by a study of cyclisation of suitable substrates, mainly 1-(2-hydroxyethyl)cyclohexanols to give hydrobenzofurans.Cyclisation traps thermodynamically stable ionic species, with rates of reaction dependent upon the size of the ether ring formed.Three- and four-membered ether rings were not formed, five-membered ether rings formed readily, the reaction being comparable in rate with a 1,2-methyl shift.Six-membered rings formed a little less readily and seven-membered rings less readily still, though a yield of 34 percent from a suitable substrate has been recorded.An unexpected feature of the reactions was their stereospecificity; in one case, this is believed to result from a methyl shift concerted with attack of the primary hydroxy group, the reaction proceeding through hindered transition state, in which methyl loss, probably as CH3+, competes with a 1,2-methyl shift.
Chemo-Selectivity of Group-VIII Metal Catalysts in Hydrogenation of Nonconjugated Enones
Ishiyama, Jun-ichi,Maeda, Satoshi,Takahashi, Kazuhiro,Senda, Yasuhisa,Imaizumi, Shin
, p. 1721 - 1726 (2007/10/02)
The chemo-selectivity of group-VIII metal catalysts has been examined in the hydrogenation of nonconjugated enones at ambient temperature under an atmospheric pressure of hydrogen.A cobalt catalyst gave high yields of unsaturated alcohols from trialkylated olefinic ketones.Osmium showed the highest selectivity among platinum metal catalysts for the reduction of the carbonyl bond in the hydrogenation of trialkylated olefinic ketones.The hydrogenation of mono- and dialkylated olefinic ketone ordinarily proceeded with a preferential saturation of the olefinic function, regardless of the catalysts.The hydrogenation of 4-methylene- and 4-ethylidenecyclohexanone was accompanied by the formation of diethyl acetals over ruthenium, rhodium, and palladium black catalysts in an ethanol solvent.The acetals were not detected in the hydrogenation of the other enones and over the other catalysts.In addition, the chemoselectivity on the hydrogenation of acyclic enones was examined over nickel and cobalt catalysts treated with small amounts of alkali and carbon monoxide.The amount of unsaturated alcohols increased when the catalyst was treated with alkali in the case of di- and trialkylated olefinic ketones, whereas the characteristics of cobalt, which selectively reduces the ketonic function in trialkylated olefinic ketoones, were completely missing when cobalt was treated with carbon monoxide.
Homolytic Displacement at Saturated Carbon. 9. The Reactions of Trichloromethanesulfonyl Chloride with Pent-4-enylcobaloximes and with Olefines. A Novel Route to (Trichloroethyl)sulfolanes via an SHi Mechanism
Ashcroft, Martyn M.,Bougeard, Peter,Bury, Adrian,Cooksey, Christopher J.,Johnson, Michael D.,et al.
, p. 1751 - 1761 (2007/10/02)
Pent-4-enylcobaloximes react with trichloromethanesulfonyl chloride in inert solvents under irradiation with tungsten lamps to give good yields of 2-(β,β,β-trichloroethyl)sulfolanes.The same products are formed in the thermal reactions in the presence of an excess of sulfur dioxide.Studies of the reactions of related olefins with trichloromethanesulfonyl chloride catalyzed by the photolysis of secondary organocobaloximes under mild conditions show that substituted 3,3,3-trichloropropyl radicals are capable of capturing sulfur dioxide.This allows us to account for the formation of the sulfolanes by a mechanism which includes a homolytic displacement of cobaloxime(II) from saturated carbon.The latter is confirmed by the observation that the isomers of 2-methyl-5-(β,β,β-trichloroethyl)sulfolane formed from (R)-hex-5-en-2-ylcobaloxime are in substantial enantiomeric excess. 3-Chloro-1,1-dioxothiacyclohexanes formed as minor products indicate that pent-4-ene-1-sulfonyl radicals cyclize to 1,1-dioxothiacyclohex-3-yl radicals rather than to the corresponding five-membered sulfolanylmethyl radicals.
