Nickel-catalyzed olefination of cyclic benzylic dithioacetals by Grignard reagents. Scope and mechanism
摘要:
The details of the first nickel-catalyzed olefination of cyclic dithioacetals to form substituted styrenes and aryl-substituted 1,4-pentadienes are described. The reaction represents a new synthetic use of the dithioacetal functionality. Only nickel complexes catalyzed these cross-coupling reactions; palladium complexes displayed no catalytic activity under the reaction conditions employed. Selective coupling occurred. A mechanism for the reaction is proposed. The experimental evidence indicates that, in these nickel-catalyzed couplings, cyclic dithioacetals are more reactive than their acyclic analogues. This increased reactivity appears to be the result of maintaining the two sulfur atoms in close proximity to each other by the use of a short chain of methylene groups.
Imidazophenanthridine ligands and metal complexes are provided. The compounds exhibit improved stability through a linking substitution that links a nitrogen bonded carbon of an imidizole ring to a carbon on the adjacent fused aryl ring. The compounds may be used in organic light emitting devices, particularly as emissive dopants, providing devices with improved efficiency, stability, and manufacturing. In particular, the compounds provided herein may be used in blue devices having high efficiency.
Drug delivery devices, sensors, and micropumps provided herein can utilize a reaction of an analyte triggered by an enzyme to drive fluid flow. In some cases, a drug delivery device can include a reservoir including a drug (e.g., insulin) and have an enzyme (e.g., glucose oxidase) positioned adjacent to said reservoir. The enzyme can catalyze a reaction of said analyte to drive a fluid flow adjacent to said reservoir to increase a release of the drug from said reservoir. A sensor for an analyte can include an enzyme bound to a surface and a flow meter to detect a flow of fluids adjacent to said surface. A self-powered enzyme micropump provided herein can provide precise control over flow rate in response to specific signals.
Diaryl thioketones are selectively reduced with ytterbium metal to diarylmethanethiols, diarylmethanes or tetraarylethylenes, via thiometallacycle intermediates which undergo electrophilic coupling at thiocarbonyl carbon and sulfur.
An organic light emitting device (OLED) is provided. The OLED has an anode, a cathode, and an emission layer, disposed between the anode and the cathode, including a first emitting compound; wherein the first emitting compound is capable of functioning as a blue phosphorescent emitter in the OLED at room temperature; wherein the first emitting compound has PLQY of less than 90% at room temperature; wherein the OLED has an external quantum efficiency of between 8% and 20% at 1 mA/cm2.
Synthetic Utility of Umpoled Diaryl Thioketone−Lanthanoid Intermediates: Desulfurization, Cross Coupling with Electrophiles, and Desulfurizative Homocoupling