100-71-0Relevant articles and documents
Deoxygenation of aldehydes and ketones using dichloro bis(1,4- diazabicyclo[2.2.2]octane)(tetrahydroborato) zirconium(IV)
Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Salehian, Fatemeh
, p. 170 - 172 (2005)
Saturated aldehydes and ketones are converted via their p-toluenesulfonyl hydrazones to the corresponding alkanes using dichloro bis(1,4-diazabicyclo[2.2. 2]octane)(tetrahydroborato) zirconium(IV) (ZrBDC). The reactions were performed in DMF-sulfolane at 110 °C and gave the corresponding alkanes in high yields. Regioselectivity in the reduction of α,β-unsaturated carbonyl groups was also observed.
Photoinduced Alkoxylation of 2-Vinylpyridinium Ion
Ishida, Akito,Uesugi, Tatsumi,Takamuku, Setsuo
, p. 1580 - 1582 (1993)
Photoirradiation of 2-vinylpyridine in acidic methanol afforded methyl 2-(2-pyridyl)ethylether in a high yield.Reactions in acetic ethanol and 2-propanol also provided the corresponding alkoxyl derivatives along with a considerable amount of 2-ethylpyridine.It was suggested that photoinduced intramolecular charge-shift from the pyridinium ion moiety into the vinyl group initiates the regioselective nucleophilic addition of alcohol.
Square Planar Cobalt(II) Hydride versus T-Shaped Cobalt(I): Structural Characterization and Dihydrogen Activation with PNP-Cobalt Pincer Complexes
Merz, Lukas S.,Blasius, Clemens K.,Wadepohl, Hubert,Gade, Lutz H.
, p. 6102 - 6113 (2019)
The carbazole-based pincer ligand R(CbzPNP)H (R = iPr, tBu) has been used for the synthesis and characterization of various low- and high-spin cobalt complexes. Upon treatment of the high-spin complexes R(CbzPNP)CoCl (2R-CoIICl) with NaHBEt3, the selective formation of cobalt(II) hydride 3iPr-CoIIH and T-shaped cobalt(I) complex 4tBu-CoI was observed, depending on the substituents at the phosphorus atoms. For an unambiguous characterization of the reaction products, a density functional theory (DFT) supported paramagnetic NMR analysis was carried out, which established the electron configuration and the oxidation states of the metal atoms, thus demonstrating the significant impact of ligand substitution on the outcome of the reaction. A distinct one-electron reactivity was found for 4tBu-CoI in the dehalogenation of tBuCl and cleavage of PhSSPh. On the other hand, the CoI species displayed two-electron redox behavior in the oxidative addition of dihydrogen. The resulting dihydride complex 6tBu-CoIII(H)2 was found to display sluggish reactivity toward alkenes, whereas the cobalt(II) hydride 3iPr-CoIIH was successfully employed in the catalytic hydrogenation of unhindered alkenes. The stoichiometric hydrogenolysis of 8iPr-CoIIBn at elevated pressure (10 bar) led to a rapid cleavage of the Co-C bond to yield hydride complex 3iPr-CoIIH. On the other hand, treatment of 2iPr-CoIICl with phenethylmagnesium chloride directly resulted in the formation of 3iPr-CoIIH, indicating facile β-H elimination of the alkene insertion product (reversibly) generated in the catalytic hydrogenation. On the basis of these observations, a mechanistic pathway involving a key σ-bond metathesis step of the CoII-alkyl species is proposed.
Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
, p. 3082 - 3087 (2020)
Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
Magnesiate Ions in Solutions and Solids Prepared from Dialkylmagnesium Compounds and Cryptands
Squiller, Edward P.,Whittle, Robert R.,Richey, Herman G.
, p. 432 - 435 (1985)
Addition of 2,1,1-cryptand to diethylmagnesium solutions greatly speeds reactions with pyridine and leads to formation of significant amounts of a 1,4- as well as a 1,2-addition product, observations attributed to formation of magnesiate species.In crystalline +(2,2,1-cryptand)>2Et6Mg22-, the magnesiums of the dianion are identical and have essentially a tetrahedral bonding geometry.They share two bridging ethyl groups.The magnesium of the cation is bonded to five of the heteroatoms of the cryptand and to the ethyl group.In crystalline NpMg+(2,1,1-cryptand)Np3Mg-, the magnesium of he anion has a trigonal planar bonding geometry.The coordination geometry of the magnesium of the cation is essentially that of a pentagonal bipyramid with bonds to all six of the heteroatoms of the cryptand and a bond to the neopentyl group.The 1H NMR spectrum of a benzene solution of this solid is consistent with the presence of the same ions in the solution.
PHOTOASSISTED COCYCLIZATION OF ACETYLENE AND NITRILES CATALYZED BY COBALT COMPLEXES AT AMBIENT TEMPERATURE AND NORMAL PRESSURE
Schulz, W.,Pracejus, H.,Oehme, G.
, p. 1229 - 1232 (1989)
In 2-position substituted pyridines have been synthesized in good yields by cocyclization of acetylene and nitriles in the presence of cobalt complexes as catalysts and by promotion of light.
Electroreductive coupling of vinylpyridines and vinylquinolines: Radical anion-substrate cycloaddition?
Janssen, Robert G.
, p. 539 - 540 (1998)
Cathodic reduction of 2- and 4-vinylpyridine and of 2-vinylquinoline gives trans-1,12-di(heteroaryl)cyclobutanes as major products; they arise via radical anion-substrate cycloaddition.
Cobalt-catalyzed ammonia borane dehydrocoupling and transfer hydrogenation under aerobic conditions
Pagano, Justin K.,Stelmach, John P. W.,Waterman, Rory
, p. 12074 - 12077 (2015)
Two cobalt compounds, Cp?Co(CO)I2 (1) and CpCo(CO)I2 (2) (Cp? = η5-C5Me5, Cp = η5-C5H5), catalyze the dehydrogenation of ammonia borane under either anaerobic or aerobic conditions and are also effective hydrogenation catalysts for alkenes and alkynes using ammonia borane as a hydrogen source, also in the presence of air.
One-pot o-nitrobenzenesulfonylhydrazide (NBSH) formation-diimide alkene reduction protocol
Marsh, Barrie J.,Carbery, David R.
, p. 3186 - 3188 (2009)
A one-pot protocol for the formation of 2-nitrobenzenesulfonylhydrazide (NBSH) from commercial reagents and subsequent alkene reduction is presented. The transformation is operationally simple and generally efficient for effecting diimide alkene reductions. A range of 16 substrates have been reduced, highlighting the unique chemoselectivity of diimide as a reduction system.
Reduction of carbon-carbon double bonds using organocatalytically generated diimide
Smit, Christian,Fraaije, Marco W.,Minnaard, Adriaan J.
, p. 9482 - 9485 (2008)
(Chemical Equation Presented) An efficient method has been developed for the reduction of carbon-carbon double bonds with diimide, catalytically generated in situ from hydrazine hydrate. The employed catalyst is prepared in one step from riboflavin (vitamin B2). Reactions are carried out in air and are a valuable alternative when metal-catalyzed hydrogenations are problematic.
