Mechanochemical Solvent-Free Catalytic C—H Methylation

The mechanochemical, solvent-free, highly regioselective, rhodium-catalyzed C-H methylation of (hetero)arenes is reported. The reaction shows excellent functional-group compatibility and is demonstrated to work for the late-stage C-H methylation of biologically active compounds. The method requires no external heating and benefits from considerably shorter reaction times than previous solution-based C-H methylation protocols. Additionally, the mechanochemical approach is shown to enable the efficient synthesis of organometallic complexes that are difficult to generate conventionally

Arynes and Their Precursors from Arylboronic Acids via Catalytic C–H Silylation

A new, operationally simple approach is presented to access arynes and their fluoride-activated precursors based on Ru-catalyzed C–H silylation of arylboronates. Chromatographic purification may be deferred until after aryne capture, rendering the arylboronates <i>de facto</i> precursors. Access to various new arynes and their derivatives is demonstrated, including, for the first time, those based on a 2,3-carbazolyne and 2,3-fluorenyne core, which pave the way for novel derivatizations of motifs relevant to materials chemistry

Palladacycles for non-redox C-C bond forming reactions

This thesis is concerned with the use of palladacyclic complexes as catalysts for C-C and C-heteroatom bond-forming reactions in which an oxidation state change of the metal centre is not part of the catalytic cycle. To this end, the investigation of a range of known K²-C,L-based palladacycles in the allylation of aldehyde and imine substrates using stannanes, as well as the 1,4-conjugate arylation of enones and imines using arylboronic acids under mild conditions is described. In each case the commercially available phosphite-based dimeric palladacycle is found to be the most active complex capable of achieving excellent conversions (>90%) at the 0.5 - 2.5mol% loading range. Three previously unknown phosphinite and amidophosphinite palladium pincer complexes are also synthesised, characterised (including crystallographically) and tested in the 1,4-conjugate addition of phenylboronic acid to chalcone and found to be inactive.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Weinreb Amides as Directing Groups for Transition Metal-Catalyzed C-H Functionalizations

Weinreb amides are a privileged, multi-functional group with well-established utility in classical synthesis. Recently, several studies have demonstrated the use of Weinreb amides as interesting substrates in transition metal-catalyzed C-H functionalization reactions. Herein, we review this part of the literature, including the metal catalysts, transformations explored so far and specific insights from mechanistic studies

Crystal structure of acetonitrile[eta(6)-1-methyl-4-(1-methylethyl)benzene][1-(pyrimidin-2-yl )-3H-indol-1-ium-2-yl-kappa N-2,C]ruthenium(II) bis-(hexafluoridoantimonate)

In the title compound, [Ru(C10H14)(C12H9N3)(CH3CN)][SbF6](2), the ruthenium(II) cation is eta(6)-coordinated by the para-cymene ligand with a Ru-centroid(eta(6)-benzene) distance of 1.746 (2) angstrom. Furthermore, ruthenium coordinations to the C and N atoms of the pyrimidyl indole ligand are found to be 1.986 (4) and 2.082 (3) angstrom, respectively. The typical piano-stool coordination environment is saturated with an acetonitrile solvent molecule with a Ru-N distance of 2.044 (3) angstrom. The indolyl ligand is protonated at the C3 position with the N=C imine bond length appropriate to that of related 3H-indole-based complexes. In the crystal, the complex cation is linked to the SbF6- ions through weak C-H center dot center dot center dot F hydrogen bonds

C4-H indole functionalisation : precedent and prospects

C4-decorated indoles feature in a plethora of bioactive and functional compounds of importance to natural product synthesis, material sciences, as well as crop protection and pharmaceutical industries. Traditionally, their syntheses largely involved harsh stoichiometric metalations and radical reactions. However, transition metal catalysed C-H activation has recently evolved into a powerful strategy for the late-stage diversification of indoles at the C4-H position. Modern photoredox, enzymatic and precious transition metal catalysis represent the key stimuli for developing challenging C-C and C-Het bond forming transformations under mild reaction conditions. Herein, we discuss the evolution and application of these methods for the step-economical transformations of otherwise inert C4-H bonds up to December 2017