A recently isolated gold(I) complex, [Au(IPr)(OH)], permits the transformation of carboxylic acids to the corresponding decarboxylated gold(I)-aryl complex without the use of silver co-catalyst under mild reaction conditions.

We report the highly efficient gold-catalyzed hydrocarboxylation of internal alkynes that operates under solvent- and silver-free conditions. This new, simple, and eco-friendly protocol allows for the synthesis of a wide variety of functionalized aryl and alkyl enol esters in high yields, with Z-stereospecificity and good regioselectivities and without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the synthesis of enol esters.

We report the use of cationic gold complexes [Au(NHC)(CH3CN)][BF4] and [{Au(NHC)}2(μ–OH)][BF4] (NHC = N-heterocyclic carbene) as highly active catalysts in the solvent-free hydroalkoxylation of internal alkynes using primary and secondary alcohols. Using this simple protocol, a broad range of (Z)-vinyl ethers were obtained in excellent yields and high stereoselectivities. The methodology allows for the use of catalyst loadings as low as 200 ppm for the addition of primary alcohols to internal alkynes (TON = 35 000, TOF = 2188 h–1).

Golden delivery: A gold(I)-NHC complex catalyses the protodecarboxylation of various (hetero)aromatic acids. This methodology is simple, highly efficient and combines both the advantages of copper and silver methods with applications to completely deactivated substrates. Moreover, intermediates in this reaction have been isolated and fully characterized and provide fundamental insights into the mechanism of protodecarboxylation with gold.

The more the merrier: Following previous investigations on the synthesis of organogold complexes by using [Au(IPr)(OH)], a high‐yielding straightforward methodology for the synthesis of gem‐diaurated and σ,π‐acetylide species via a dinuclear gold hydroxide complex [{Au(IPr)}2(μ‐OH)][BF4] (see scheme) has now been developed.

Thei mproved synthesis of g-, d-a nd elactones using ad inuclear N-heterocyclic carbene (NHC)-gold(I) catalyst is reported. This solventfree process provides access to g-a nd d-lactones in high regio-and stereoselectivity.R eactions were performed at low catalyst loadings andw ithout the need for any additives.T he use of adigold pre-catalyst providesanew synthetic route to functionalised e-lactones,p oorly accessible using previous methodologies.

The direct functionalization of hydrocarbon chains represents a stepeconomical approach to tetrahedral carbon-rich functionalized organic intermediates from cheap and abundant feedstock, and has recently been a topic of intense investigations.[1] Two main strategies employing transition-metal catalysts have been pursued to tackle this challenging synthetic problem: [2] inner-sphere C-H activation, involving concerted C-H bond cleavage and carbon-metal bond formation, and outer-sphere C-H activation, not involving organometallic intermediates, which show distinct selectivity profiles. In most reported inner-sphere reactions, a directing group is employed to control the site-selectivity of the C-H bond cleavage, whereas non-directed methods are scarce.[1b] The transition metal-catalyzed C-H borylation reactions developed by Hartwig and co-workers constitute notable examples, wherein terminal-selective activation and functionalization of alkyl chains is achieved by steric control (Scheme 1a). [3,4] This borylation reaction can be followed by a Pd-catalyzed Suzuki-Miyaura cross-coupling in order to create a C-C bond at the same position (2 → 3), with the inconvenient that two noble metals are employed in this two-step sequence.[5] A conceptually different strategy is reported herein (Scheme 1b). Secondary bromoalkanes 4 are readily available compounds, which can be generated by bromination of abundant feedstock such as alkenes, alcohols, or even alkanes 1. The generation of an alkylzinc halide 5 from 4 by metal insertion, [6] followed by transmetallation to an in situ-generated organopalladium complex [Pd(R 2 )YL] would form the corresponding branched alkylpalladium intermediate 6. The latter would migrate to the terminal position (→ 7) via a succession of b-H elimination, rotation and insertion steps induced by a suitable ancillary ligand, where it would undergo reductive elimination to give the linear product 3. [7,8] Ligand-controlled Pd 0 -catalyzed migrative couplings have been investigated by our group using enolates as nucleophiles [9] or organozinc compounds obtained by Boc-directed lithiation and Li-Zn transmetallation.[10] In the current work, we show that terminal (linear) cross-coupling products 3 can be obtained in a regioconvergent manner in just one step from bromoalkanes 4 under operationally simple, Barbier (in situ) conditions. In addition, in most cases a similar selectivity pattern is obtained regardless of the position of the bromine atom in the alkyl chain. This observation led us to employ mixtures of bromides 4' obtained by radical bromination of linear alkanes 1. Indeed, this process is known to give rise to mixtures of secondary bromides, [11] and hence has been of little synthetic use so far. However, we reasoned that this mixture could be productively utilized by applying the same in situ metal insertion/migrative Negishi coupling sequence, wherein a mixture of branched organopalladium intermediates 6' would converge to the same linear complex 7,

In gold chemistry, the hydroxide function on the metal center was observed to act as a potent transmetalation group facilitator when reacted with boronic acids leading to the exceedingly rapid formation of gold-aryl bonds.