Heteroarylboronates in Rhodium-Catalyzed 1,4-Addition to Enones

Rhodium­(I)-catalyzed 1,4-addition of aryl and alkenylboronic acids to α,β-unsaturated carbonyl compounds is well established, but the transfer of heteroaryl residues in this reaction remains underdeveloped. We have studied heteroaryl MIDA and pinacol boronates as alternatives to the labile boronic acid counterparts. Under racemic conditions, 12 adducts with heteroaryl residues, among them unsubstituted 3- and 4-pyridinyl, 2-furanyl, thienyl, and pyrrolyl groups, were obtained in moderate to excellent yields. The enantioselective version of the reaction proved highly sensitive to the electronic character of the heteroaryl substituents, with boronates carrying electron-rich residues giving modest to high yields but consistently high enantiomeric excesses

Efficient Pseudo-enantiomeric Carbohydrate Olefin Ligands

Highly efficient pseudo-enantiomeric olefin ligands were designed from d-glucose and d-galactose. These ligands yield consistently excellent levels of enantioselectivity in Rh(I)-catalyzed 1,4-additions of aryl- and alkenylboronic acids to achiral enones and high diastereoselectivity with chiral substrates. Contrary to established olefin ligands, they are obtained enantiomerically pure via short syntheses without racemic resolution steps, making them a valuable addition to the arsenal of chiral ligands with olefinic donor sites

Conformal and Highly Luminescent Monolayers of Alq₃ Prepared by Gas-Phase Molecular Layer Deposition

The gas-phase molecular layer deposition (MLD) of conformal and highly luminescent monolayers of tris­(8-hydroxyquinolinato)­aluminum (Alq₃) is reported. The controlled formation of Alq₃ monolayers is achieved for the first time by functionalization of the substrate with amino groups, which serve as initial docking sites for trimethyl aluminum (TMA) molecules binding datively to the amine. Thereby, upon exposure to 8-hydroxyquinoline (8-HQ), the self-limiting formation of highly luminescent Alq₃ monolayers is afforded. The growth process and monolayer formation were studied and verified by in situ quartz crystal monitoring, optical emission and absorption spectroscopy, and X-ray photoelectron spectroscopy. The nature of the MLD process provides an avenue to coat arbitrarily shaped 3D surfaces and porous structures with high surface areas, as demonstrated in this work for silica aerogels. The concept presented here paves the way to highly sensitive luminescent sensors and dye-sensitized metal oxides for future applications (e.g., in photocatalysis and solar cells)