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化學系外文文獻翻譯中英文(編輯修改稿)

2025-01-11 09:21 本頁面
 

【文章內容簡介】 ium(Ⅱ ) acetate and N,Nbis(2,6diisopropylphenyl) dihydro imidazolium chloride 1 (2 mol%) were used to catalyze the carbonylative coupling of aryl diazonium tetrafluoroborate salts and aryl boronic acids to form aryl ketones. Optimal conditions include carbon monoxide (1 atm) in 1,4dioxane at 100℃ for 5 h. Yields for unsymmetrical aryl ketones ranged from 76 to 90% for isolated materials with only minor amounts of biaryl coupling product observed (212%). THF as solvent gave mixtures of products. 1,4Dioxane proved to be the superior solvent giving higher yields of ketone product together with less biphenyl formation. At room temperature and at 0℃ with 1 atm CO, biphenyl became the major product. Electronrich diazonium ion substrates gave a reduced yield with increased production of biaryl product. Electrondeficient diazonium ions were even better forming ketones in higher yields with less biaryl byproduct formed. 2Naphthyldiazonium salt also proved to be an effective substrate givingketones in the excellent range. Base on above palladium NHC catalysts, aryl diazonium tetrafluoroborates have been coupled with arylboron pounds, carbon monoxide, and ammonia to give aryl amides in high yields. A saturated yVheterocyclic carbene (NHC) ligand, H2lPr 1 was used with palladium(II) acetate to give the active catalyst. The optimal conditions with 2mol% palladiumNHC catalyst were applied with various anoboron pounds and three aryl diazonium tetrafluoroborates to give numerous aryl amides in high yield using pressurized CO in a THF solution saturated with ammonia. Factors that affect the distribution of the reaction products have been identified and a mechanism is proposed for this novel fourponent coupling plexes are monly formed from an imidazolium salt using strong base. Deprotonation occurs at C2 to give a stable carbene that adds to form a aplex with the metal. Crystals were obtained from the reaction of imidazolium chloride with sodium t butoxide, Nal and palladium(II) acetate, giving a dimeric palladium(II) iodide NHC plex . The structure adopts a flat, 4membered ring u2 bridged arrangement as seen in a related dehydro NHC plex formed with base. We were pleased to find that chloride, treated with palladium(II) acetate without adding base or halide in THF, also produced suitable crystals for Xray anaysis. In contrast to the diiodide, the palladiumcarbenes are now twisted out of plane, adopting a nonplanar 4ring core. The borylation of aryldiazonium tetrafluoroborates with bis(pinacolatoborane) was optimized using
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