Alba Collado

Straightforward synthesis of [Au(NHC)X] (NHC = N-heterocyclic carbene, X = Cl, Br, I) complexes.

An improved protocol for the synthesis of [Au(NHC)X] (X = Cl, Br, I) complexes is reported. This versatile one-step synthetic methodology proceeds under mild conditions, in air, using technical grade solvents, is scalable and is applicable to a wide range of imidazolium and imidazolidinium salts.

Ruthenium-Catalyzed (2 + 2) Intramolecular Cycloaddition of Allenenes

We report a ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenes and alkenes. We have found that the use of the ruthenium complex RuH(2)Cl(2)(P(i)Pr(3))(2), which has previously gone unnoticed in catalytic applications, is crucial for the observed reactivity. The reaction proceeds under mild conditions and is fully diastereoselective, providing a practical entry to a variety of bicyclo[3.2.0]heptane skeletons featuring cyclobutane rings.

Gold–Acetonyl Complexes: From Side-Products to Valuable Synthons

A new synthetic strategy was devised leading to the formation of complexes, such as [Au(IPr)(CH2 COCH3)]. The approach capitalizes on the formation of a decomposition product observed in the course of the synthesis of [Au(IPr)(Cl)]. A library of gold acetonyl complexes containing the most common N-heterocyclic carbene (NHC) ligands has been synthesized. These acetonyl complexes are good synthons for the preparation of numerous organogold complexes. Moreover, they have proven to be precatalysts in common gold(I)-catalyzed reactions.

Gold(I)‐Assisted α‐Allylation of Enals and Enones with Alcohols

The intermolecular α-allylation of enals and enones occurs by the condensation of variously substituted allenamides with allylic alcohols. Cooperative catalysis by [Au(ItBu)NTf2] and AgNTf2 enables the synthesis of a range of densely functionalized α-allylated enals, enones, and acyl silanes in good yield under mild reaction conditions. DFT calculations support the role of an α-gold(I) enal/enone as the active nucleophilic species.

Synthesis, characterisation, and oxygen atom transfer reactions involving the first gold(I)-alkylperoxo complexes

The synthesis of a new class of organogold species containing a peroxo moiety is reported. Complexes [Au(IPr)(OO(t)Bu)] and [Au(SIPr)(OO(t)Bu)] have been synthesised via a straightforward methodology using the parent gold(I) hydroxide complexes as synthons. These complexes have been successfully used in oxygen-transfer reactions to triphenylphosphine.

Influence of bulky yet flexible N-heterocyclic carbene ligands in gold catalysis.

Summary Three new Au(I) complexes of the formula [Au(NHC)(NTf2)] (NHC = N-heterocyclic carbene) bearing bulky and flexible ligands have been synthesised. The ligands studied are IPent, IHept and INon which belong to the ‘ITent’ (‘Tent’ for ‘tentacular’) family of NHC derivatives. The effect of these ligands in gold-promoted transformations has been investigated.

Chapter 16:Sustainable Homogeneous Gold Catalysis

The field of homogeneous gold chemistry has extraordinarily expanded in recent decades. As a consequence, a myriad of gold-catalysed transformations have been reported. However, the focus has been on the development of new reactivity, rather than on developing sustainable processes. Therefore, in order to raise awareness of the importance of sustainable chemistry, in this chapter we will discuss relevant aspects and selected examples of homogeneous gold catalysis that comply with the “12 Principles of Green Chemistry”. Among the selected examples are: the use of well-defined catalysts that render the use of additives unnecessary; efficient transformations promoted at very low catalyst loadings; solvent-free transformations or reactions promoted in water or ionic liquids; oxidation reactions using green oxidants; and finally, transformations that can be carried out at room temperature.