Enantioselective Crossed Photocycloadditions of Styrenic Olefins by Lewis Acid Catalyzed Triplet Sensitization

The synthesis of unsymmetrical cyclobutanes by controlled heterodimerization of olefins remains a substantial challenge, particularly in an enantiocontrolled fashion. Shown herein is that chiral Lewis acid catalyzed triplet sensitization enables the synthesis of highly enantioenriched diarylcyclobutanes by photocycloaddition of structurally varied 2′‐hydroxychalcones with a range of styrene coupling partners. The utility of this reaction is demonstrated through the direct synthesis of a representative norlignan cyclobutane natural product.     

Catalytic Enantioselective Synthesis of Highly Functionalized Difluoromethylated Cyclopropanes

The first catalytic asymmetric synthesis of highly functionalized difluoromethylated cyclopropanes is described. The method, based on a rhodium‐catalyzed cyclopropanation of difluoromethylated olefins, gives access to a broad range of cyclopropanes bearing ester, ketone, or nitro functional groups. By using Rh₂((S )‐BTPCP)₄ as a catalyst, the corresponding products were obtained in high yields and high diastereo‐ and enantioselectivities (up 20:1 d.r. and 99 % ee ). This methodology allowed preparation of enantioenriched difluoromethylcyclopropanes for the first time.     

Bright,Multi‐responsive,Sky‐Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework

A new class of highly efficient and stable, blue‐phosphorescent Pt^II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching—from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi‐response phenomenon. Highly efficient singlet‐oxygen sensitization by the Pt^II compounds yields UV‐light‐induced phosphorescence enhancement and color switching.