C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• . Unfortunately, with this catalyst, repeatability problems were detected (yield fluctuation of approximately 20%) which could be assigned to the low solubility of this catalyst in toluene. In order to overcome these problems, we synthesized triruthenium carbonyl complexes with phosphine ligand(s), namely

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• highest for the pyrido-annelated carbene. Going from the free carbene to the Rh(CO)2Cl(NHC) complexes, the increase in occupancy of the complete π-system of the carbene ligand upon coordination is lowest for the pyrido-annelated carbene and highest for the saturated carbene. Keywords: carbonyl complexes

• carbodicarbenes [50][51], in which the carbon atom has a formal oxidation state of ±0 (Figure 1) [52][53][54]. Earlier, we had prepared their tungsten and chromium carbonyl complexes, but could not find deviations of the CO stretching frequencies from those of analogous NHC complexes [55]. As this might be due to

• desired carbonyl complexes 2a and 2b from the respective COD complex 1 [56] by ligand exchange under a 13CO atmosphere of 6 bar in CD2Cl2 in a pressure-NMR tube according to Scheme 1. At first, a precipitate forms which is redissolved shortly after and a color change of the solution from light yellow to

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• carbene tetracarbonyl tungsten complexes. Oxidative additions of XY bonds to low-coordinate W(CO)n fragments is a common reactivity pattern for tungsten carbonyl complexes [75][76][77][78][79][80] and appears to be operative in the present case as well. Experimental studies on the formation of imine E-3

• ) solution in 1,2-dichloroethane under reflux (ca. 84 °C) shows that W(CO)5(E-2) simply decays to a carbonyl-free species (likely the dark precipitate) and no soluble CO-containing intermediates such as W(CO)4(E-2), W(CO)4(Z-2) or hydrido carbonyl complexes are detected (Supporting Information File 1, Figure

• complex W(CO)4(Z-3). All other conceivable pathways, namely 1,2-H shifts within the free carbene or within the carbonyl complexes W(CO)5(E-2) or W(CO)4(E-2), are significantly more energy demanding. The possibility of a seven-coordinate tungsten(II) intermediate opens the oxidative addition/pseudorotation

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• as prepared by controlled living ring-opening metathesis polymerization (ROMP) of the respective metal-incorporating monomers. Ferrocene- and other metallocene-modified polymers, macromolecules including metal-carbonyl complexes, polymers tethering early or late transition metal complexes, etc. are

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• rhodium carbonyl complexes 9–11. Synthesis of rhodium complexes 12 and 13. Selective formation of complex 14 under 40 bar CO/H2 at 80 °C. Possible mechanism for the hydroformylation of styrene when using monophosphine complexes 12 or 13 as precatalysts. Simplified Heck coupling mechanism when using

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• on transition metal promoted rearrangements of bicyclo[1.1.0]butanes [11]. Thus Ru–carbonyl complexes promote the rearrangement of 1,2,2-trimethylbicyclo[1.1.0]butane (1) to yield diene 2 and the cyclopropyl derivative 3 (Scheme 1, reaction 1: a,b for 2 and 3), whilst pentafluorophenylcopper tetramer

Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

• César A. Urbina-Blanco,
• Xavier Bantreil,
• Hervé Clavier,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2010, 6, 1120–1126, doi:10.3762/bjoc.6.128

• their respective steric parameter. Results and Discussion Evaluation of the ligand electronic and steric properties Previous studies have shown that the electronic parameter of NHC (and other) ligands can be quantified employing the stretching frequency of CO (νCO) in various transition metal–carbonyl

• complexes [26][27][28][29][30][31][32]. This method was initially developed by Tolman [33], using the average infrared frequency of CO in [Ni(CO)3L] complexes. This electronic parameter has become known as the Tolman electronic parameter (TEP) and has been used to quantify the electron donor ability of