A radical C–H arylation reaction of oxazoles with (hetero)aryl iodides using Cs2CO3 as base/electron donor and 1,1′-bis(diphenylphosphino) ferrocene (dppf) as a catalytic SET mediator is reported. The overall reaction likely follows the general base-promoted homolytic aromaticsubstitution mechanism through a radical-chain pathway. DFT calculations suggest that dppf forms a complex with CsCO3–, enhancing
报道了使用Cs 2 CO 3作为碱/电子给体和1,1'-双(二苯基膦基)二茂铁(dppf)作为催化SET介体,恶唑与(杂)芳基碘化物的自由基CH芳基化反应。整个反应可能通过自由基链途径遵循一般的碱促进的均质芳族取代机理。DFT计算表明,dppf与CsCO 3 –形成络合物,增强了SET还原能力,可从ArI生成芳基。
Photoinduced Copper-Catalyzed C−H Arylation at Room Temperature
作者:Fanzhi Yang、Julian Koeller、Lutz Ackermann
DOI:10.1002/anie.201512027
日期:2016.4.4
Room‐temperature azole C−H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site‐selective C−H arylations of non‐aromatic oxazolines under mild reaction conditions, and provides step‐economical access to the alkaloid natural products balsoxin and texamine.
An efficient synthesis of 2,5-disubstitutedoxazolesvia Co(III) catalysis is described herein. The synthesis is achieved under mild conditions through [3+2] cycloaddition of N-pivaloyloxyamides and alkynes. The reaction operates through an internal oxidation pathway and features a very broad substrate scope. The one-step synthesis of natural products such as texamine and balsoxin has been demonstrated