Herein, we report that merging palladium catalysis with hydrogen atom transfer (HAT) photocatalysis enabled direct arylations and alkenylations of aldehyde C–H bonds, facilitating visible light-catalyzed construction of a variety of ketones. Tetrabutylammonium decatungstate and anthraquinone were found to act as synergistic HAT photocatalysts. Density functional theory calculations suggested a Pd0–PdII–PdIII–PdI–Pd0
在本文中,我们报道了钯催化与氢原子转移(HAT)光催化的合并使醛C–H键的直接芳基化和烯基化成为可能,从而促进了可见光催化的各种酮的构建。发现四丁基癸酸铵和蒽醌可作为HAT的协同光催化剂。密度泛函理论计算表明,Pd 0 -Pd II -Pd III -Pd I -Pd 0途径,并揭示了在存在KHCO 3的情况下,Pd 0催化剂和光催化剂的再生同时发生。这种再生具有低能垒,促进了钯催化循环与光催化循环的有效耦合。本文报道的工作表明,HAT光催化在钯催化的交叉偶联和CH官能化反应中的进一步应用有望成功。
2-Pyridyl and 3-pyridylzinc bromides: direct preparation and coupling reaction
作者:Seung-Hoi Kim、Reuben D. Rieke
DOI:10.1016/j.tet.2010.02.061
日期:2010.4
A facile synthetic approach to the direct preparation of 2-pyridyl and 3-pyridylzinc bromides has been demonstrated usingRieke zinc with 2-bromopyridine and 3-bromopyridine, respectively. A variety of different electrophiles have been coupled with the resulting organozinc reagents to give the corresponding cross-coupling products in moderate to good yields.
A Facile Synthetic Approach to the Preparation of 3-Pyridyl Derivatives: Preparations and Coupling Reactions of 3-Pyridylzinc and Its Analogues
作者:Reuben Rieke、Seung-Hoi Kim、Tim Slocum
DOI:10.1055/s-0029-1217000
日期:2009.11
A facile synthetic approach to the direct preparation of 3-pyridylzinc bromide has been demonstrated usingRieke zinc with 3-bromopyridine in the presence of a catalytic amount of lithium chloride. A variety of different electrophiles have been coupled to give the corresponding cross-coupling products in moderate to good yields. Also, this methodology has been expanded to the preparation of the corresponding
Double Duty for Cyanogen Bromide in a Cascade Synthesis of Cyanoepoxides
作者:Zhou Li、Vladimir Gevorgyan
DOI:10.1002/anie.201006966
日期:2011.3.14
An unprecedented reaction mode of cyanogenbromide has been discovered. Under basic conditions, cyanogenbromide acts as an equivalent of both Br+ and CN− to convert enolizable ketones into the corresponding cyanoepoxides in good yields. This unique reaction mode provides new, one‐pot access to densely substituted cyanoepoxides from easily available ketones (see scheme).
One-Pot Arylative Epoxidation of Ketones by Employing Amphoteric Bromoperfluoroarenes
作者:Zhou Li、Vladimir Gevorgyan
DOI:10.1002/anie.201106969
日期:2012.1.27
A one‐pot cascade synthesis of perfluoroaryl oxiranes 2 by the arylativeepoxidation of enolizable ketones 1 with bromopentafluorobenzene (PFPBr) and derivatives (3) is reported. PFPBr is utilized as an equivalent of Br+ and PFP− in this highly efficient, easily scaled‐up, diastereoselective epoxidation reaction, which produces synthetically useful polyfluoroaryl oxiranes.