Conventional, hadronic matter consists of baryons and mesons made of three quarks and a quark–antiquark pair, respectively1,2. Here, we report the observation of a hadronic state containing four quarks in the Large Hadron Collider beauty experiment. This so-called tetraquark contains two charm quarks, a $$\overline{{{{{u}}}}}$$ u ¯ and a $$\overline{{{{{d}}}}}$$ d ¯ quark. This exotic state has a mass of approximately 3,875 MeV and manifests as a narrow peak in the mass spectrum of D0D0π+ mesons just below the D*+D0 mass threshold. The near-threshold mass together with the narrow width reveals the resonance nature of the state.

We herein report the unprecedented synthesis of diverse biologically important aza-heterocycles by employing sulfilimines as nitrene transfer reagents.T his class of sulfurbased aza-ylides had not been successfully used for gold nitrene transfer before.T his work contains an efficient generation of a-imino gold carbenes by N À Sc leavage of sulfilimines.T hese gold carbenes undergo C À Hi nsertion, cyclopropanation, and nucleophilic attacktoform indoles (44 examples), 3-azabicyclo[3.1.0]hexan-2-imines (24 examples), and imidazoles (3 examples).Our study represents au nique gold-catalyzed reaction between alkynes and sulfur ylides,and also includes the first aza-heterocycle synthesis that proceeds by intermolecular nitrene transfer followed by cyclopropanation of the a-imino gold carbenes.M oreover,a nu nexpected synthesis of 4-acylquinolines (3 examples) from 2-acylphenyl sulfilimines and propargylic silyl ether derivatives by a1 ,2hydride shift onto the a-imino gold carbene and asubsequent Mukaiyama aldol cyclization was discovered.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

The first X-ray crystal structures of mono- and dipyridoimidazolinylidenes are presented, and the size of the carbene N-C-N angles discussed and correlated with the 13C NMR chemical shifts.

Different furans containing an ynamide or alkynyl ether moiety in the side chain were prepared. The gold-catalyzed transformation of these compounds delivered dihydroindole, dihydrobenzofuran, chroman, and tetrahydroquinoline derivatives at room temperature through very fast reactions. Furthermore, the stabilizing effect of the heteroatom directly attached to the intermediate arene oxides led to highly selective reactions, even in the case of only mono-substituted furans, which is quite different from previous results obtained with non-heteroatom-substituted alkynes.