查看更多>>摘要：A weak Bronsted base-promoted photoredox catalysis has been developed for the direct C-H alpha-alkyla-tion of heteroarenes with cyclic and acyclic ethers. The high efficiency of this strategy is demonstrated by the mild reaction conditions, broad substrate scope, economical reagents and high regioselectivity. With air as the sole oxidant, a set of alkylated heteroarenes were accessed smoothly. This strategy was also applied for late-stage functionalization of valuable vitamin E nicotinate and loratadine. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A copper-catalyzed oxidative cross-dehydrogenative coupling (CDC) strategy of secondary phosphine oxides and alcohols for the synthesis of various phosphinate esters was proposed. Under the mild reaction conditions (CuCl2 center dot 2H(2)O/K2S2O8, at room temperature for 3-12 h under air), a variety of substrates were well-tolerated and afforded the desirable compounds in moderate to excellent yields. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Two new pincer-type bisnitroxides have been synthesized, where tetramethylenedioxy and o-xylylenedioxy are chosen as a bridge between the p-position of two tert-butyl phenyl nitroxide moieties. The X-ray crystal structure analysis clarified the linear and U-shaped molecular structures for the former and latter compounds, respectively. In the toluene solution ESR of the tetramethylenedioxy derivative, five hyperfine splitting lines were recorded, but a center signal was somewhat lowered. The ESR spectra of the o-xylylenedioxy derivative displayed a typical 1/2/3/2/1 five-line pattern at 370 K, and an "alternating line-width " effect appeared in 210-230 K. These spectra were reproduced by simulation, based on the proposed model where a few conformers have differing exchange couplings. The contribution showing strong exchange is reasonably ascribable to the U-shaped conformer. Thus, the solid and solution experimental results are compatible with each other.
查看更多>>摘要：A highly stereoselective asymmetric Henry reaction using a double fluorous-tagged Co-salen complex was conducted. The introduction of two fluorous tags into the Co-salen complex was found to be more effective in terms of improving stereoselectivity than the introduction of a strong electron-withdrawing nitro group into the same position of the salen ligand. The observed stereoselectivity was significantly higher than that when using a Jacobsen-type Co-salen complex bearing the same asymmetric source. (c) 2022 Elsevier Ltd. All rights reserved.
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