A new protocol has been developed for the synthesis of benzo[d]isoxazole through a palladium-catalyzed C–H bond functionalization–[4 + 1] annulation pathway.
The C-H activation strategy has become one of the preferred methods to introduce chemical functionality to a chemically inert carbon atom. Intensive efforts have been devoted to developing either versatile bond formations (product structural diversity) or effective directing groups (substrate site selectivity). From the views of medicinal and synthetic practitioners, the C-H activation approach remains inadequate due to its limitation to pointto-point derivatization. Direct assembly of 3D molecular complexity in a single step remains elusive for this strategy. Towards this goal, a multitasking functional group is required to accomplish several missions in one pot: site selecitivity, cleavability and redox versatility. We demonstrate that an oxyacetamide group is such a multifunctional warhead that enables a series of C-H functionalization cascades and allows direct access to structurally diverse polycyclic heterocyles in one pot. The progress of these reaction cascades were fully controlled by oxidants and temperature. The proliferation of the reaction chain can be extended to a four-step cascade.
An efficient Rh(III)-catalyzed coupling reaction of N-phenoxyacetamides with α,β-unsaturated aldehydes to give 1,2-oxazepines via C-H activation/[4+3] annulation has been developed. This transformation does not require oxidants and features C-C/C-N bond formation to yield seven-membered oxazepine rings at room temperature. Further derivation of 1,2-oxazepines leads to important chroman derivatives.
Using an internally oxidizing directing group (DG) strategy, we report a Rh(III)-catalyzed synthesis of isoquinolones via C-H activation/annulation of benzoylhydrazines and alkynes. Tunable double cascade cyclization of benzoylhydrazines with two equivalents of alkynes led to tetracyclic amides. These N-heterocycles demonstrated adjustable AIE properties.
β-Ga2O3nanorods are prepared by hydrothermal method and characterized by X-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectra. The results reveal that high crystallinity, monoclinic phase ofβ-Ga2O3nanorods were prepared with a diameter of about 60 nm and length of 500 nm. Photoluminescence study indicates that theβ-Ga2O3nanorods exhibit a broad blue light emission at room temperature. Theβ-Ga2O3nanorods displayed high photocatalytic activity under simulated solar irradiation; after 2 h irradiation, over 95% of methylene blue solution and over 90% of methyl orange solution were decolorized. Since this process does not require additional hydrogen peroxide and uses solar light, it can be developed as an economically feasible and environmentally friendly method to treat dye effluent.
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