Clear cut: For the title reaction, O(2), the ideal oxidant, was used as the only oxidizing reagent. The dimer intermediate (see scheme) and isotopic labeling control experiments with (18)O(2) partially disclosed the reaction mechanism.

An efficient and mild copper-catalyzed one-pot approach toward ynediones has been established. A variety of ynediones were constructed directly through oxidative coupling of alkyne with α-hydroxy ketone. Oxygen-oxidizing and neutral conditions in one-pot for a wide range of substrates including natural product derivatives make this transformation highly efficient and practical. On the basis of control experiments, in situ IR measurements, and isotopic labeling experiments, a plausible mechanism involving intermediate phenylglyoxal was drawn. Applications by synthesis of various heterocycles were also investigated.

Copper-catalyzed, aerobic, oxidative, C3-dicarbonylation of indoles has been realizedd irectly from a-hydroxyketones,w hich serve as an efficient dicarbonylative reagent under mild conditions. The method is widely compatibility with various functional groups, offering as traightforward means to produce differenth eterocyclesubstituted quinoxalines in excellent yields. These diverse fluorescent quinoxalines exhibited photophysical properties and solvatochromism in certain rules. Based on control experiments, ap lausible reaction mechanism was proposed.Scheme1.1,2-Dionemotif and important quinoxaline derivatives.Scheme2.Oxygenationand green oxidation of a-hydroxyketones controlled by reaction conditions.

Klarer Schnitt: Für die Titelreaktion wurde O2, das ideale Oxidans, als einziges Oxitationsmittel verwendet. Das Dimerintermediat (siehe Schema) und Isotopenmarkierungsexperimente mit 18O2 konnten teilweise den Reaktionsmechanismus aufklären.

Ag eneral strategy for synthesis of heterocyclic hemiketal-containing a,b-unsaturated ketones has been established.U sing the environmentally sound and readily available reagents water and thiourea applied to ynediones, as eries of sensitive hemiketals of 3(2 H)-furanones and 3(2 H)-thienones were constructed under mild conditions. Both of the reaction conditions are compatible with ad iverse range of functional groups. Isotopic labeling, tautomerism, and GC-MS trackingm ethods were used to reveal the mechanisms.