Gold-catalyzed domino cyclization-alkynylation reactions with EBX reagents: new insights into the reaction mechanism.

Gold-catalyzed domino processes constitute a useful alternative to C-H functionalization for the synthesis of functionalized (hetero)arenes. Herein, we report computational studies on the gold-catalyzed cyclization alkynylation of keto-allenes with ethynylbenziodoxole (EBX) reagents, which identified a gold(i) picolinate complex as the active catalyst, giving the first mechanistic insights into this transformation.

A one-pot route to thioamides discovered by gas-phase studies: palladium-mediated CO extrusion followed by insertion of isothiocyanates.

A new palladium mediated "one pot" synthesis of thioamides from aromatic carboxylic acids (ArCOH + RNCS → ArC(S)NHR + CO) was discovered by gas-phase experiments and theoretical studies. Palladium-mediated decarboxylation of aromatic carboxylic acids followed by addition of substituted isothiocyanates leads to the corresponding thioamide derivatives.

Gas-Phase Ion-Molecule Reactions of Copper Hydride Anions [CuH] and [CuH].

Gas-phase reactivity of the copper hydride anions [CuH] and [CuH] toward a range of neutral reagents has been examined via multistage mass spectrometry experiments in a linear ion trap mass spectrometer in conjunction with isotope labeling studies and Density Functional Theory (DFT) calculations. [CuH] is more reactive than [CuH], consistent with DFT calculations, which show it has a higher energy HOMO. Experimentally, [CuH] was found to react with CS via hydride transfer to give thioformate (HCS) in competition with the formation of the organometallic [CuCS] ion via liberation of hydrogen; CO via insertion to produce [HCuOCH]; methyl iodide and allyl iodide to give I and [CuHI]; and 2,2,2-trifluoroethanol and 1-butanethiol via protonation to give hydrogen and the product anions [CuH(OCHCF)] and [CuH(SBu)].

A Mechanistic Investigation of the Gold(III)-Catalyzed Hydrofurylation of C-C Multiple Bonds.

The gold-catalyzed direct functionalization of aromatic C-H bonds has attracted interest for constructing organic compounds which have application in pharmaceuticals, agrochemicals, and other important fields. In the literature, two major mechanisms have been proposed for these catalytic reactions: inner-sphere syn-addition and outer-sphere anti-addition (Friedel-Crafts-type mechanism). In this article, the AuCl-catalyzed hydrofurylation of allenyl ketone, vinyl ketone, ketone, and alcohol substrates is investigated with the aid of density functional theory calculations, and it is found that the corresponding functionalizations are best rationalized in terms of a novel mechanism called "concerted electrophilic ipso-substitution" (CEIS) in which the gold(III)-furyl σ-bond produced by furan auration acts as a nucleophile and attacks the protonated substrate via an outer-sphere mechanism.