A magnetically separable palladium catalyst was simply synthesized through a wet impregnation incorporating palladium nanoparticles and superparamagnetic Fe3O4 nanoparticles in KBH4 solution, which is a highly efficient catalyst for the carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes under phosphine-free conditions. This catalyst is completely magnetically recoverable due to the super paramagnetic behavior of Fe3O4 and can be reused with sustained selectivity and activity.

A discrete-element approach is employed to model the transport, collision, adhesion, and deposition of small colloidal particles in a spin coating process. The computations are used to predict particle distribution and wall adhesion during the nonevaporative phase of spin coating of a thin film, which is important for controlling the abrasiveness, opacity, conductivity, and other properties of the film, as well as for using the deposited particles for growing new materials (e.g., nanotubes). The computations examine the particle distribution and the effect of particle adhesive force on particle deposition during spin coating. Particles are observed to preferentially collect within the film ridge just behind the moving contact line. An increase in the particle adhesive force is observed to lead to enhanced deposition of particles within an inner radius of the film and increase in the aggregate size.

A computational study is reported of the instability and growth of fingers for liquid films driven over heterogeneous surfaces. Computations are performed using a variation of the precursor-film model, in which a disjoining pressure term is used to introduce variation in the static contact angle, which in turn models surface heterogeneity. The formulation is shown to yield results consistent with the Tanner–Hoffman–Voinov dynamic contact angle formula for sufficiently small values of the precursor film thickness. A modification of the disjoining pressure coefficient is introduced which yields correct variation of dynamic contact angle for finite values of the precursor film thickness. The fingering instability is examined both for cases with ordered strips of different static contact angle and for cases with random variation in static contact angle. Surface heterogeneity is characterized by strip width and amplitude of static contact angle variation for the case with streamwise strips and by correlation length and variance of the static contact angle variation from its mean value for the random distribution case.

Herein, we report a gold-catalyzed oxidative coupling reaction of terminal alkynes and borane adducts for the synthesis of α-boryl carbonyl compounds, which are versatile organoboron reagents and could undergo various synthetic transformations. This efficient, regiospecific reaction showed good functional group tolerance and could be used for late-stage modification of structurally complex bioactive compounds.

A series of chiral NCN pincer Pd(II) complexes with 1,3-bis(2′-imidazolinyl)phenyl (Phebim) ligands were synthesized via the C–H activation or oxidative addition method. A dinuclear macrocyclic Pd(II) complex was also prepared by reaction of the Phebim-H ligand with PdCl2. All of the new compounds were fully characterized, and X-ray single-crystal structures were obtained for two of the complexes. The Pd(II) complexes were successfully applied to enantioselective hydrophosphination of various enones with diphenylphosphine, providing optically active phosphine derivatives in good yields with enantioselectivities of up to 94% ee.

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Catalytic asymmetric reactions in which water is a substrate are rare. Enantioselective transition-metal-catalyzed insertion of carbenes into the O–H bond of water can be used to incorporate water into the stereogenic center, but the reported chiral catalysts give good results only when α-aryl-α-diazoesters are used as the carbene precursors. Herein we report the first highly enantioselective O–H bond insertion reactions between water and α-alkyl- and α-alkenyl-α-diazoesters as carbene precursors, with catalysis by a combination of achiral dirhodium complexes and chiral phosphoric acids or chiral phosphoramides. Participation of the phosphoric acids or phosphoramides in the carbene transfer reaction markedly suppressed competing side reactions, such as β-H migration, carbene dimerization, and olefin isomerization, and thus ensured good yields of the desired products. Fine-tuning of the ester moiety facilitated enantiocontrol of the proton transfer reactions of the enol intermediates and resulted in excellent enantioselectivity. This protocol represents an efficient new method for preparation of multifunctionalized chiral α-alkyl and α-alkenyl hydroxyl esters, which readily undergo various transformations and can thus be used for the synthesis of bioactive compounds. Mechanistic studies revealed that the phosphoric acids and phosphoramides promoted highly enantioselective [1,2]- and [1,3]-proton transfer reactions of the enol intermediates. Maximization of molecular orbital overlap in the transition states of the proton transfer reactions was the original driving force to involve the proton shuttle catalysts in this process.

Enantioselective transition-metal-catalyzed carbene insertion into Si–H bonds is a promising method for preparing chiral organosilicons; however, all the carbene precursors used to date in this reaction have been diazo compounds, which significantly limits the structural diversity of the resulting chiral organosilicons. Herein, we report a protocol for rhodium-catalyzed asymmetric Si–H bond insertion reactions that use functionalized alkynes as carbene precursors. With chiral dirhodium tetracarboxylates as catalysts, the reactions of carbonyl-ene-ynes and silanes smoothly gave chiral organosilanes in high yields (up to 98%) with excellent enantioselectivity (up to 98% ee). Kinetic studies suggest that insertion of the in situ-generated rhodium carbenes into the Si–H bonds of the silanes is probably the rate-determining step. This work represents the first enantioselective Si–H bond insertion reaction using alkynes as carbene precursors and opens the door for preparing chiral organosilicons with unprecedented structural diversity from readily available alkynes.