98468-96-3Relevant academic research and scientific papers
Copper-Catalyzed Cyanation of Aryl- and Alkenylboronic Reagents with Cyanogen Iodide
Okamoto, Kazuhiro,Sakata, Naoki,Ohe, Kouichi
, p. 4670 - 4673 (2015)
Direct catalytic cyanation of organoboronic acids with cyanogen iodide has been achieved by using a copper-bipyridine catalyst system. The cyanation reaction is likely to occur through two catalytic cycles: copper(II)-catalyzed iodination of organoboronic acids and the following cyanidocopper(I)-mediated cyanation of organic iodides.
Catalytic claisen rearrangement by intercepting ketenimines with propargylic alcohols: A strategy to generate and transform ketenimines from radicals
Yan, Xuyang,Liu, Hongchi,Wei, Shenquan,Huang, Hanmin
supporting information, p. 6794 - 6798 (2020/09/15)
An efficient strategy for facilitating the cross-coupling of two radicals has been established via the coordination of a radical with a metal catalyst. This strategy provides a remarkable ability to harness the reactivity of nitrile-containing azoalkanes and enables a novel cascade reaction with nitrile-containing azoalkanes and propargylic alcohols to be established. By using this reaction, a range of acetylenic and allenic amides were obtained that provides a versatile platform for further derivatizations.
Kinetics and Mechanism of the Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes
Bartholomeyzik, Teresa,Pendrill, Robert,Lihammar, Richard,Jiang, Tuo,Widmalm, G?ran,B?ckvall, Jan-E.
supporting information, p. 298 - 309 (2018/01/17)
Pd-catalyzed C-C bond-forming reactions under oxidative conditions constitute a class of important and widely used synthetic protocols. This Article describes a mechanistic investigation of the arylating carbocyclization of allenynes using boronic acids and focuses on the correlation between reaction conditions and product selectivity. Isotope effects confirm that either allenic or propargylic C-H activation occurs directly after substrate binding. With an excess of H2O, a triene product is selectively formed via allenic C-H activation. The latter C-H activation was found to be turnover-limiting and the reaction zeroth order in reactants as well as the oxidant. A dominant feature is continuous catalyst activation, which was shown to occur even in the absence of substrate. Smaller amounts of H2O lead to mixtures of triene and vinylallene products, where the latter is formed via propargylic C-H activation. The formation of triene occurs only in the presence of ArB(OH)2. Vinylallene, on the other hand, was shown to be formed by consumption of (ArBO)3 as a first-order reactant. Conditions with sub-stoichiometric BF3·OEt2 gave selectively the vinylallene product, and the reaction is first order in PhB(OH)2. Both C-H activation and transmetalation influence the reaction rate. However, with electron-deficient ArB(OH)2, C-H activation is turnover-limiting. It was difficult to establish the order of transmetalation vs C-H activation with certainty, but the results suggest that BF3·OEt2 promotes an early transmetalation. The catalytically active species were found to be dependent on the reaction conditions, and H2O is a crucial parameter in the control of selectivity.
Asymmetric Synthesis of Triarylmethanes by Rhodium-Catalyzed Enantioselective Arylation of Diarylmethylamines with Arylboroxines
Huang, Yinhua,Hayashi, Tamio
supporting information, p. 7556 - 7559 (2015/07/01)
The reaction of racemic diarylmethylamines, (Ar1Ar2CHNR2), where Ar1 is substituted with a 2-hydroxy group, with arylboroxines (Ar3BO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral triarylmethanes (Ar1Ar2CH?Ar3) with high enantioselectivity (up to 97% ee). The reaction is assumed to proceed through o-quinone methide intermediates which undergo Rh-catalyzed asymmetric 1,4-addition of the arylboron reagents.
Scalable synthesis of oxazolones from propargylic alcohols through multistep palladium(II) catalysis: β-selective oxidative heck coupling of cyclic sulfonyl enamides and aryl boroxines
Alamsetti, Santosh Kumar,Persson, Andreas K. A.,Jiang, Tuo,Baeckvall, Jan-E.
supporting information, p. 13745 - 13750 (2014/01/06)
A whale of a scale: The title oxidative Heck coupling proceeded with unusual β selectivity to generate a variety of branched substituted oxazolones (see scheme; Ts=p-toluenesulfonyl). The three-step synthesis from readily available starting materials with a simple palladium catalyst and inexpensive reagents could be carried out in a single reaction vessel or scaled up for the preparation of large amounts of these amino acid precursors. Copyright
Ruthenium-catalyzed conversion of sp3 C-O bonds in ethers to C-C bonds using triarylboroxines
Ogiwara, Yohei,Kochi, Takuya,Kakiuchi, Fumitoshi
supporting information; experimental part, p. 3254 - 3257 (2011/08/02)
Catalytic conversion of unreactive sp3 C-O bonds in alkyl ethers to C-C bonds is described. Alkyl ethers bearing 2- or 4-pyridyl groups were coupled with triarylboroxines in the presence of a ruthenium catalyst. Triarylboroxines bearing a variety of functional groups including electron-withdrawing and -donating groups can be used for the reaction. No additional base was required for the coupling with the organoboron reagents, and base-sensitive groups can be tolerated. The reaction is considered to proceed via dehydroalkoxylation followed by addition of triarylboroxines to form C-C bonds.
