A new, one-step route to N-heterocyclic oxo-carbene complexes (NHOCs), representatives of chemo-switchable NHC complexes, is reported. This simple procedure provides an easy access to gold, palladium and platinum complexes of these ligands.

Readily available phenols can be converted into substituted aryl alkynyl ethers, which react with an N‐oxide as an oxidant and catalytic amounts of a Brønsted acid to provide benzofuranones. If non‐terminal alkynyl ethers are applied, a 1,2‐hydride shift takes place and phenyl acrylates are obtained. Thus activated alkynes can serve as α‐oxy carbene precursors even in the absence of a metal catalyst.

Different arylgold(i), one alkynylgold(i), and one vinylgold(i) triphenylphosphane complexes were subjected to electrophilic halogenation reagents. With N-chlorosuccinimid, N-bromosuccinimid, and N-iodosuccinimid as well as the Barluenga reagent, selectively halogenated compounds were obtained. Trifluoroacetic acid, as a source of protons, leads to a clean protodeauration. With N-fluorobenzenesulfonimide or Selectfluor, exclusively a homocoupling was observed. For the precursor of the vinylgold(i) complex, a similar oxidative coupling could be induced by gold(iii) chloride. Reactions with silicon or tin electrophiles failed.

In am odular template synthesis,unsaturated NHC complexes of gold, palladium andp latinum were synthesizedf rom simplem etal salts,i sonitriles and aminesw ith acetal or ketal groups.U pon the addition of aminesw ith tethereda cetal or ketal moieties to the metal-activated isonitrile,f irst nitrogen acyclic carbene (NAC)c omplexes are formed. These undergo ring closure and elimination to the unsaturated NHC complexes upon addition of acid. This simples trategyo pens an attractive and fast approach to NHC complexes of gold, palladium and platinum. Them odular approach allowsafast modification and is well-suited for the synthesiso fu nsymetrically and symmetricallys ubstituted unsaturated NHC complexes.Scheme 1. NHC-Synthesis via metal isonitrile precursors; left:i ntermolecular process,r ight:i ntramolecular process.

Under the conditions of dual activation catalysis with oxygen nucleophiles, β‐substituted naphthalenes were obtained from 1,2‐diethinyl arenes. Mechanistic studies, which include isotope labeling experiments, support that dual activation leads to β‐substituted naphthalenes, whereas α‐naphthalenes are formed by π activation only, and no gold acetylide or dual activation is involved in the formation of the α‐substituted products. Additional experiments on substrates that led to dibenzopentalenes support these mechanistic insights.