Verification of a model to predict the influence of particle inertia and gravity on a decaying turbulent particle-laden flow

In an earlier publication some of the authors presented a theoretical model for the calculation of the influence of particle inertia and gravity on the turbulence in a stationary particle-laden flow. In the present publication the model is extended for application to a decaying suspension. Also a comparison is given between predictions made with the model and experimental data (own data and data reported in the literature) on a decaying turbulent flow with particles in a water tunnel or in a wind tunnel. For most of the experiments a prediction with reasonable accuracy and an interpretation is possible by means of the model.     

Ruthenium‐Catalyzed C?C Coupling of Fluorinated Alcohols with Allenes: Dehydrogenation at the Energetic Limit of β‐Hydride Elimination

Ruthenium(II) complexes catalyze the C C coupling of 1,1‐disubstituted allenes and fluorinated alcohols to form homoallylic alcohols bearing all‐carbon quaternary centers with good to complete levels of diastereoselectivity. Whereas fluorinated alcohols are relatively abundant and tractable, the corresponding aldehydes are often not commercially available because of their instability.     

Template-induced and molecular recognition directed hierarchical generation of supramolecular assemblies from molecular strands

The linear oligo-isophthalamide strand 1 undergoes a conformational reorganization upon binding of a cyanuric acid template as effector to afford a helical disklike object possessing radially disposed alkyl residues. Solvophobic and stacking interactions, in turn, drive a "second level" self-assembly of the templated structure, the stacking of the helical disks, to yield fibers as revealed by electron microscopy. These data provide insight into the interplay of the different structural and interactional features of the molecular components towards the formation of supramolecular fibers through sequential hierarchical self-assembly events and suggest design strategies for the effector-controlled generation of related supramolecular assemblies.     

Catalytic addition of metallo-aldehyde enolates to ketones: a new C-C bond-forming hydrogenation

The first catalytic cross-aldolization of metallo-aldehyde enolates with ketone acceptors is enabled via hydrogenation of keto-enals with cationic rhodium catalysts. These results, in conjunction with prior studies involving the catalytic hydrogen-mediated reductive coupling of enones, dienes, and diynes with carbonyl acceptors, support the feasibility of developing a broad new class of catalytic C-C bond formations based on the electrophilic trapping of hydrogenation intermediates. [reaction: see text]     

Chemically induced anion radical cycloadditions: intramolecular cyclobutanation of bis(enones) via homogeneous electron transfer

The first examples of anion radical cycloaddition induced by homogeneous electron transfer from chemical agents are described. Specifically, upon exposure to chrysene anion radical, bis(enone) substrates are found to engage in stereoselective intramolecular [2 + 2] cycloaddition. These studies, along with the corresponding electrochemically initiated reactions, provide insight into this fundamentally new pattern of reactivity and support the feasibility of expanding this novel reaction type.     

Regioselective Hydrohydroxyalkylation of Styrene with Primary Alcohols or Aldehydes via Ruthenium‐Catalyzed C−C Bond Forming Transfer Hydrogenation

Transfer hydrogenative coupling of styrene with primary alcohols using the precatalyst HClRu(CO)(PCy₃)₂ modified by AgOTf or HBF₄ delivers branched or linear adducts from benzylic or aliphatic alcohols, respectively. Related 2‐propanol mediated reductive couplings also are described.     

Total Synthesis of Cryptocaryol A by Enantioselective Iridium‐Catalyzed Alcohol C−H Allylation

The polyketide natural product cryptocaryol A is prepared in 8 steps via iridium catalyzed enantioselective diol double C?H allylation, which directly generates an acetate‐based triketide stereodiad. In 4 previously reported total syntheses, 17–28 steps were required.