Reduction of Alkyl Halides by Triethylsilane Based on a Cationic Iridium Bis(phosphinite) Pincer Catalyst: Scope, Selectivity and Mechanism
作者:Jian Yang、Maurice Brookhart
DOI:10.1002/adsc.200800528
日期:2009.1
hydride 2,6-bis[di-(tert-butyl)phosphinyloxy)phenyl(hydrido)iridium, (POCOP)IrH+ POCOP= 2,6-[OP(t-Bu)2]2C6H3} binds and activates the silane. This complex serves as a potent silylating reagent to generate silyl halonium ions, Et3SiXR+, which are reduced by the neutral iridium dihydride to yield alkane product and regenerate the cationic (POCOP)IrH+, thus closing the catalytic cycle. All key intermediates
已经发现并开发了一种基于阳离子铱双(次亚膦酸酯)夹钳催化剂的三乙基硅烷还原各种烷基卤化物的高效方法。与传统的基于自由基的方法以及三氯化铝/三乙基硅烷(AlCl 3 / Et 3 SiH)和三苯基甲基四[五氟苯基]硼酸酯/三乙基硅烷[Ph 3 C] [B(C 6 F 5)4 ] / Et 3SiH}系统。相对于卤化物,还原使用三当量的三乙基硅烷,并且可以在非常低的催化剂负载量下并且以无溶剂的方式进行,这可以为环境上有吸引力的和安全的替代方案提供许多目前实践中的还原烷基卤的方法。机理研究揭示了独特的催化循环。阳离子氢化铱2,6-双[二-(叔丁基)次膦酰氧基)苯基(氢化)铱(POCOP)IrH + POCOP = 2,6- [OP(t- Bu)2 ] 2 C 6 H 3 }结合并激活硅烷。该络合物用作有效的甲硅烷基化试剂,可生成甲硅烷基ha离子Et 3 SiXR +被中性的二氢化铱还原,生成