Functionalized α-oximinoketones as building blocks for the construction of imidazoline-based potential chiral auxiliaries

Synthesis and characterization of Pt(II) and Au(I) complexes with N-oxy-heterocyclic carbene ligands (NOHCs)

Two N-alkyloxy-N'-phenylimidazolium proligands and the corresponding platinum(II) cyclometalated N-alkyloxyimidazol-2-ylidene complexes with β-diketonate auxiliary ligands, [(CNOHC^C*)Pt(L∩L)] (L∩L = acetyacetonate (acac) or 1,3-bis(2,4,6-trimethylphenyl)-propane-1,3-dionato (mesacac)) were synthesized and fully characterized. In addition, a Au(I) monocarbene complex was synthesized, isolated and characterized. Solid-state structures of two cyclometalated platinum(II) NOHC complexes and the Au(I) NOHC complex were obtained providing structural proof.

Visible-Light-Mediated Alkylation of Thiophenols via Electron Donor-Acceptor Complexes Formed between Two Reactants

A metal-free, photocatalyst-free, photochemical system was developed for the direct alkylation of thiophenols via electron donor-acceptor (EDA) complexes (K_EDA = 145 M^-1) between two reactants, N-hydroxyphthalimide esters as acceptors and thiophenol anions as donors, in the presence of a tertiary amine. The EDA complexes in the reaction system have a broad range of visible-light absorption (400-650 nm) and can trigger the reaction effectively under sunlight.

Enantiopure 4-oxazolin-2-ones and 4-methylene-2-oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

Enantiopure 3-((R)- and 3-((S)-1-phenylethyl)-4-oxazoline-2-ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N-(R)- or N-(S)-1-phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4- and 5-positions of the 4-oxazolin-2-one ring through thermal and MW-promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade process into fused six-membered carbo- and heterocycles. The structure of the reaction products depended on the electrophiles and reaction conditions used. Alternative isomeric 4-methylene-2-oxazolidinones served as chiral precursors for a versatile and divergent approach to highly substituted cyclic carbamates. DFT quantum calculations showed that the formation of bicyclic pyranyl compounds was generated by a diastereoselective concerted hetero-Diels-Alder cycloaddition.

Continuous generation, in-line quantification and utilization of nitrosyl chloride in photonitrosation reactions

The reagent is prepared from stable, inexpensive and readily available starting materials. In-line UV/vis monitoring enables determination of the reagent's concentration after a continuous extraction and liquid–liquid separation sequence.