C–H Functionalization Reactivity of a Nickel–Imide

This article discusses C-H functionalization reactivity of a Nickel-Imide

Preparation of unsymmetrical ketones from tosylhydrazones and aromatic aldehydes via formyl C–H bond insertion

Preparation of ketones by insertion of diazo compounds into the formyl C−H bond of an aldehyde is an attractive procedure, but use of structurally diverse diazo compounds is hampered by preparation and safety issues. A convenient procedure for the synthesis of unsymmetrical ketones from bench-stable tosylhydrazones and aryl aldehydes is reported. The procedure can be performed in one pot from the parent carbonyl compound and needs only a base, with no additional promoters being required

Selective Synthesis of N-Substituted 1,2-Dihydropyridines from Furans by Copper-Induced Concurrent Tandem Catalysis

8 páginas, 4 figuras, 1 tabla, 9 esquemasA novel transformation in which mono- or dialkyl-substituted furans are converted into 1,2-dihydropyridines upon reaction with PhI═NTs at room temperature is reported. The reaction is catalyzed by complexes of general formula TpxM (M = Cu, Ag) and consists of a one-pot procedure with four consecutive catalytic cycles. Furan aziridination is followed by aziridine ring-opening, transimination reaction, inverse-electronic-demand aza-Diels−Alder reaction, and a final hydrogen elimination reaction. The mechanism of the overall transformation is proposed where the metal complex displays a crucial role along the reaction pathway.Financial support of this work by MEC (CTQ2008-00042/BQU and Consolider Ingenio 2010, Grant No. CSD2006-0003) is acknowledged.Peer reviewe

Evidencing an inner-sphere mechanism for NHC-Au(I)-catalyzed carbene-transfer reactions from ethyl diazoacetate

Kinetic experiments based on the measurement of nitrogen evolution in the reaction of ethyl diazoacetate (N2CHCO2Et, EDA) and styrene or methanol catalyzed by the [IPrAu]+ core (IPr = 1,3-bis(diisopropylphenyl)imidazole-2-ylidene) have provided evidence that the transfer of the carbene group CHCO2Et to the substrate (styrene or methanol) takes place in the coordination sphere of Au(I) by means of an inner-sphere mechanism, in contrast to the generally accepted proposal of outer-sphere mechanisms for Au(I)-catalyzed reactions

Synthesis, Structural Characterization, and Catalytic Activity of IPrNi(styrene)2 in the Amination of Aryl Tosylates

[EN] A novel bis-styrene IPrNi0 derivative has been synthesized from the reaction of Ni(COD)2 and free 1,3-bis(2,6-diisopropylphenyl)imidazolidene (IPr) ligand in the presence of styrene. The complex has been characterized by spectroscopic data as well as by X-ray crystallography. Its catalytic performance in the amination reaction of aryl tosylates is also reported. The catalytic reactions proceed in a very selective manner, affording moderate to high yields of cross-coupling products in short reaction times at 110 °C.This research was financially supported by the MINECO (Proyecto CTQ2011-24502 and Consolider Ingenio 2010, Grant No. CSD2006-003) and the Junta de Andalucia (Proyecto P07-FQM-02745). M.J.I. thanks the Junta de Andalucia for a research fellowship.Iglesia, MJ.; Blandez, JF.; Fructos, MR.; Prieto, A.; Alvarez, E.; Belderrain, TR.; Nicasio, MC. (2012). Synthesis, Structural Characterization, and Catalytic Activity of IPrNi(styrene)2 in the Amination of Aryl Tosylates. Organometallics. 31(17):6312-6316. https://doi.org/10.1021/om300566mS63126316311

Catalytic copper-mediated ring opening and functionalization of benzoxazoles

© 2014 American Chemical Society. A novel reaction involving benzoxazole, ethyl diazoacetate, and water has been discovered, with TpBr3Cu(NCMe) (TpBr3 = hydrotris(3,4,5-tribromopyrazolyl)borate) as the catalyst. The fused azoles are converted into highly functionalized substituted benzenes bearing aldehyde, amine carboxylate and hydroxyl groups. The protocol has been applied for a series of benzoxazoles with several diazo compounds. Experimental data and theoretical calculations have led to a mechanistic proposal that includes carbene addition, ylide formation, and water addition to the latter, all those steps being catalyzed by the copper center.Peer Reviewe