Palladium and Lewis-Acid-Catalyzed Intramolecular Aminocyanation of Alkenes: Scope, Mechanism, and Stereoselective Alkene Difunctionalizations

An expansion of methodologies aimed at the formation of versatile organonitriles, via the intramolecular aminocyanation of unactivated alkenes, is herein reported. Importantly, the need for a rigid tether in these reactions has been obviated. The ease-of-synthesis and viability of substrates bearing flexible backbones has permitted for diastereoselective variants as well. We demonstrated the utility of this methodology with the formation of pyrrolidones, piperidinones, isoindolinones, and sultams. Furthermore, subsequent transformation of these motifs into medicinally relevant molecules is also demonstrated. A double crossover ¹³C-labeling experiment is consistent with a fully intramolecular cyclization mechanism. Deuterium labeling experiments support a mechanism involving <i>syn</i>-addition across the alkene

Synthesis of ZnO Nanoparticles with Controlled Shapes, Sizes, Aggregations, and Surface Complex Compounds for Tuning or Switching the Photoluminescence

The electronic energy transfer (EET) usually induces the fluorescence self-quenching, but it has been positively used here to tune and/or switch the photoluminescence (PL) of ZnO nanoparticles (NPs). Monodisperse ZnO nanospheres, rods, tripods, and clusters with tunable sizes have been synthesized to reproducibly and finely control the NP aggregation because EET is sensitive to the interparticle separation. The complex reactions between these NPs and their dispersion media have been used to further control the EET for tuning the ZnO PL. By changing the NP concentrations, shapes, and/or the cluster sizes, the band-edge UV PL of the ZnO NPs dispersed in alcohol or water is modified in both intensity and peak position, and new blue emissions with tunable intensity around 418, 435, and 468 nm are induced. As confirmed by the X-ray diffraction patterns and the infrared, PL, absorption, and Raman spectra, the ZnO NPs made here can slowly react with ethanol to form a new composite ZnO–(C₂H₅OH)_<i>n</i>, which changes the EET between NPs and leads to strong blue PL around 435 nm. By simply using different dispersion media (such as ethanol or water) to modify the surface complex compounds of ZnO NPs, the 435 nm blue PL can be turned on or off

Intramolecular Oxyacylation of Alkenes Using a Hydroxyl Directing Group

Alkene oxyacylation is a new strategy for the preparation of β-oxygenated ketones. Now, with Ir catalysis and low-cost salicylate esters, alkene oxyacylation can be promoted by simple and versatile hydroxyl directing groups. This paper discusses catalyst optimization, substituent effects, mechanistic experiments, and the challenges associated with asymmetric catalysis. Crossover experiments point to several key steps of the mechanism being reversible, including the most likely enantiodetermining steps. The oxyacylation products are also prone to racemization without catalyst when heated alone; however, crossover is not observed without catalyst. These observations account for the low levels of enantioinduction in alkene oxyacylation. The versatility of the hydroxyl directing group is highlighted by demonstrating further transformations of the products

Synthesis of ZnO Nanoparticles with Controlled Shapes, Sizes, Aggregations, and Surface Complex Compounds for Tuning or Switching the Photoluminescence

The electronic energy transfer (EET) usually induces the fluorescence self-quenching, but it has been positively used here to tune and/or switch the photoluminescence (PL) of ZnO nanoparticles (NPs). Monodisperse ZnO nanospheres, rods, tripods, and clusters with tunable sizes have been synthesized to reproducibly and finely control the NP aggregation because EET is sensitive to the interparticle separation. The complex reactions between these NPs and their dispersion media have been used to further control the EET for tuning the ZnO PL. By changing the NP concentrations, shapes, and/or the cluster sizes, the band-edge UV PL of the ZnO NPs dispersed in alcohol or water is modified in both intensity and peak position, and new blue emissions with tunable intensity around 418, 435, and 468 nm are induced. As confirmed by the X-ray diffraction patterns and the infrared, PL, absorption, and Raman spectra, the ZnO NPs made here can slowly react with ethanol to form a new composite ZnO–(C₂H₅OH)_<i>n</i>, which changes the EET between NPs and leads to strong blue PL around 435 nm. By simply using different dispersion media (such as ethanol or water) to modify the surface complex compounds of ZnO NPs, the 435 nm blue PL can be turned on or off

Intramolecular Oxyacylation of Alkenes Using a Hydroxyl Directing Group

Alkene oxyacylation is a new strategy for the preparation of β-oxygenated ketones. Now, with Ir catalysis and low-cost salicylate esters, alkene oxyacylation can be promoted by simple and versatile hydroxyl directing groups. This paper discusses catalyst optimization, substituent effects, mechanistic experiments, and the challenges associated with asymmetric catalysis. Crossover experiments point to several key steps of the mechanism being reversible, including the most likely enantiodetermining steps. The oxyacylation products are also prone to racemization without catalyst when heated alone; however, crossover is not observed without catalyst. These observations account for the low levels of enantioinduction in alkene oxyacylation. The versatility of the hydroxyl directing group is highlighted by demonstrating further transformations of the products