The development of a robust and high-yielding ring-closing metathesis (RCM) reaction and its demonstration on multikilogram scale are described. A detailed understanding of the impact of impurities on the RCM reaction was achieved using a variety of chemical and statistical methods. Specifically, individual impurities were evaluated in spiking studies to identify those that negatively affected the RCM reaction. Projection methods (PCA and PLS) were applied to historical data to identify the main sources of variation in starting material quality and determine the main detrimental impurities that impeded the RCM reaction. The synthesis of the starting material was then modified to adequately control these key impurities, which in turn ensured a robust RCM process. Finally, the robustness of the RCM reaction was assessed using a probability-based approach.

Dehydrative cyclization of diols to O-heterocycles is attractive, but acid and/or metal-based catalysts are generally required. Here, we present a hydrogen-bond donor and acceptor cooperative catalysis strategy for the synthesis of O-heterocycles from diols in ionic liquids [ILs; e.g., 1-hydroxyethyl-3-methyl imidazolium trifluoromethanesulfonate ([HO-EtMIm][OTf])] under metal-free, acid-free, and mild conditions. [HO-EtMIm][OTf] is tolerant to a wide diol scope, shows performance even better than H2SO4, and affords a series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines, dioxanes, and thioxane in high yields. Mechanism investigation indicates that the IL cation and anion serve as hydrogen-bond donor and acceptor, respectively, to activate the C─O and O─H bonds of alcohol via hydrogen bonds, which synergistically catalyze dehydrative cyclization of diols to O-heterocycles. Notably, the products could be spontaneously separated after reaction because of their immiscibility with the IL, and the IL could be recycled. This green strategy has great potential for application in industry.

A novel gamma-MnO(2) hollow structure has been synthesized at room temperature using a simple chemical reaction between MnSO(4) and KMnO(4) in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. The synthesized gamma-MnO(2) hollow structure was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET analysis. It was found that the hollow structure consisting of short gamma-MnO(2) nanorods with diameters of 5-10 nm and lengths of 50-100 nm could form when the MnSO(4)/KMnO(4) mole ratio was equal to or larger than 2.3. The excess amount of Mn(2+) in solution was observed to promote the crystallization of gamma-MnO(2) nanorods and the formation of the gamma-MnO(2) hollow structure. In addition, the evolution of microstructure and morphology of the products obtained with a MnSO(4)/KMnO(4) mole ratio of 2.3 at different reaction times revealed that the hollow structure was formed via an Ostward ripening process. Furthermore, the obtained gamma-MnO(2) hollow structure was found to exhibit a better catalytic performance than conventional gamma-MnO(2) in the aerobic oxidation of benzyl alcohol to benzaldehyde, demonstrating its possible application in alcohol oxidation.