C–H Bond Arylations and Benzylations on Oxazol(in)es with a Palladium Catalyst of a Secondary Phosphine Oxide
摘要:
An air-stable, well-defined palladium complex derived from secondary phosphine oxide (SPO) (1-Ad)(2)P(O)H enabled efficient C-H bond functionalizations with ample scope, which set the stage for direct arylations and benzylations of (benz)oxazoles, as well as unprecedented palladium-catalyzed C-H bond arylations on nonaromatic oxazolines.
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。
Palladium-Catalyzed Direct Arylations, Alkenylations, and Benzylations through C−H Bond Cleavages with Sulfamates or Phosphates as Electrophiles
A catalytic system comprised of Pd(OAc)2 and bidentate ligand dppe enabled first direct arylations with moisture-stable aryl sulfamates as electrophiles, and proved applicable to unprecedented C−H bond functionalizations with easily accessible alkenyl phosphates as well as benzyl phosphates.