Synthesis of new copper(<scp>i</scp>) complexes with tris(2-pyridyl) ligands. Applications to carbene and nitrene transfer reactions
作者:Julio Pérez、Dolores Morales、Luis A. García-Escudero、Héctor Martínez-García、Daniel Miguel、Pablo Bernad
DOI:10.1039/b812604f
日期:——
New copper(I) complexes with tris(2-pyridyl)methane (TPC), tris(2-pyridyl)methoxymethane (TPM) and tris(2-pyridyl)amine (TPN) ligands have been synthesized and characterized, including structural determinations by X-ray diffraction of some examples. Their activity as catalysts in carbene and nitrenetransferreactions was studied.
Regioselective and Enantioselective Intermolecular Buchner Ring Expansions in Flow
作者:Gabrielle S. Fleming、Aaron B. Beeler
DOI:10.1021/acs.orglett.7b02537
日期:2017.10.6
The firstexample of a regioselective and enantioselective intermolecular Buchner ring expansion is reported using continuous flow. The practicality and scope of the reaction are greatly improved under flow conditions. Reactions of ethyl diazoacetate with symmetric and nonsymmetric arenes afford cycloheptatrienes in good yield and excellent regioselectivity. The firstexample of an asymmetric intermolecular
Mechanistic Studies on Gold-Catalyzed Direct Arene C–H Bond Functionalization by Carbene Insertion: The Coinage-Metal Effect
作者:Manuel R. Fructos、Maria Besora、Ataualpa A. C Braga、M. Mar Díaz-Requejo、Feliu Maseras、Pedro J. Pérez
DOI:10.1021/acs.organomet.6b00604
日期:2017.1.9
The catalytic functionalization of the C-sp(2)-H bond of benzene by means of the insertion of the CHCO2Et group from ethyl diazoacetate (N-2=CHCO2Et) has been studied with the series of coinage-metal complexes IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) and NaBAr4F (BAr4F = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate). For Cu and Ag, these examples constitute the first use of such metals toward this transformation, which also provides ethyl cyclohepta-2,4,6-trienecarboxylate as a byproduct from the so-called Buchner reaction. In the case of methyl-substituted benzenes, the reaction exclusively proceeds onto the aromatic ring, the C-sp(2)-H bond remaining unreacted. A significant coinage-metal effect has been observed, since the gold catalyst favors the formation of the insertion product into the C-sp(2)-H bond whereas copper and silver preferentially induce the formation of the cycloheptatriene derivative. Experimental studies and theoretical calculations have explained the observed selectivity in terms of the formation of a common Wheland intermediate, resembling an electrophilic aromatic substitution, from which the reaction pathway evolves into two separate routes to each product.
Transition-metal-catalyzed reactions of diazo compounds. 2. Addition to aromatic molecules: catalysis of Buchner's synthesis of cycloheptatrienes
作者:A. J. Anciaux、A. Demonceau、A. F. Noels、A. J. Hubert、R. Warin、P. Teyssie
DOI:10.1021/jo00318a010
日期:1981.2
Kinetic Separation and Asymmetric Reactions of Norcaradiene Cycloadducts: Facilitated Access via H<sub>2</sub>O-Accelerated Cycloaddition
作者:William D. Mackay、Jeffrey S. Johnson
DOI:10.1021/acs.orglett.5b03577
日期:2016.2.5
We exploit the Buchner reaction to access 1,2-disubstituted cyclohexadiene synthons (norcaradienes), which participate in H2O-accelerated cycloaddition with dieneophiles to provide cyclopropyl-fused [2.2.2]-bicyclooctene derivatives in good yields. Regioisomeric mixtures can be kinetically separated by exploiting different reaction rates in Diels Alder reactions. Meso-Diels-Alder products may be enantioselectively desymmetrized, providing highly substituted cyclohexanes with up to seven contiguous stereocenters.