Jung Yun Kim

A multicomponent multicatalyst reaction (MC)(2)R for constructing fully substituted 1,2,3-triazoles is reported. An application of chemoselectivity and latent catalysis in a sequence of multicatalytic reactions confers control over a number of undesired processes, where all of the reagents coexist in the same reaction vessel. The sequence of a chemoselective copper-catalyzed azide alkyne cycloaddition followed by a palladium/copper-catalyzed Sonogashira cross-coupling afforded 1,2,3-triazoles regioselectively with good to high yields and a broad scope.

A robust method for the dual-metal-catalyzed combination of organic azides, terminal alkynes, and internal alkynes is reported. The reaction is initiated with a chemoselective copper-catalyzed azide alkyne cycloaddition (CuAAC) followed by a palladium-catalyzed incorporation of an internal alkyne. The simple one-pot procedure introduces C–H functionalization to the growing field of multicomponent multicatalytic reactions ((MC)2R). With inexpensive CuI and the Herrmann–Beller palladacycle as catalysts, four bonds and two heterocyclic rings are created with HI as the sole byproduct. The broad scope with respect to all components showcases this versatile transformation, leading to a new class of fully substituted polycyclic triazoles. 1H NMR and deuterium-labeling studies provide insight into the rate differences of the copper and palladium steps.

The pyroelectricity of polar materials provides great potential for electricity generation from waste heat. The pyroelectric effect of the material can be magnificently enhanced at a first-order phase transformation due to the abrupt jump in spontaneous polarization within a narrow temperature range. Here, we show that the performance of energy conversion by phase transformation is inversely resonant with the hysteresis of thermally driven structural transformations in a (Ba1−xSrx) (Hf0.02Ce0.005Ti0.975)O3 system, corresponding to a singular lattice distortion mode satisfying the crystallographic compatibility condition. Among the finely tuned Sr compositions from 0.04 to 0.10, we discovered that Sr0.07 composition is a promising material candidate in this material system for pyroelectric energy conversion. Our work suggests a rational strategy of material development for pyroelectric energy conversion applications.

In modern synthetic chemistry, the formation of multiple C-C bonds in a limited number of steps to access both diversity and complexity has become an important challenge. In recent years, significant research has been devoted to the synthesis of 1,2,3-triazole containing compounds in a multimetal-catalyzed domino sequence due to the remarkable biological activity and pharmaceutical potency of these compounds. Considering the increasing significance of 1,2,3-triazoles in synthetic chemistry, mixing all of the starting components in a one-pot, one-step process to create the final triazole product will be highly efficient with respect to time, cost and simplicity of performance. A number of published papers illustrated the diverse applications of 1,2,3-triazoles (e.g., palladium-mediated couplings and direct C-H bond functionalization). Similarly, this work demonstrates the development of a highly efficient and practical approach to the synthesis of these versatile triazole-containing motifs via a one-pot, one-step cascade process that involves Sonogashira, Heck and carbopalladation/annulation reactions.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.