Khamespanah Fatemeh, Gerken James B, Mannel David S, Nagy Sandor, Kimmich Barbara, Stahl Shannon S
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
LyondellBasell, Houston Technology Center, 8280 Sheldon Road, Channelview, TX 77530, USA.
Organometallics. 2024 Jul 8;43(13):1502-1510. doi: 10.1021/acs.organomet.4c00218. Epub 2024 Jun 18.
The reductive coupling of CO and alkenes represents a compelling strategy for the synthesis of carboxylic acids. In this study, we show that Ni(OAc) and 6,6'-Mebpy (dmbpy) catalyzes hydrocarboxylation of terminal unactivated alkenes to afford the branched 2-methyl-substituted carboxylic acids. The nickel/dmbpy speciation in solution is elucidated through electrochemical and UV-visible and NMR spectroscopic methods. A catalyst deactivation process is identified, involving competitive reduction of CO to CO resulting in formation of an inactive Ni-CO complex. The Ni catalyst may be reactivated by oxidative treatment of the Ni-CO complex to release CO; however, the results highlight an important complication that can arise in Ni-catalyzed reductive coupling reactions with CO.
CO与烯烃的还原偶联是合成羧酸的一种极具吸引力的策略。在本研究中，我们表明Ni(OAc)₂和6,6'-Mebpy（dmbpy）催化末端未活化烯烃的氢羧化反应，生成支链的2-甲基取代羧酸。通过电化学、紫外可见光谱和核磁共振光谱方法阐明了溶液中的镍/dmbpy物种。确定了一种催化剂失活过程，该过程涉及CO竞争性还原为CO，导致形成无活性的Ni-CO络合物。通过对Ni-CO络合物进行氧化处理以释放CO，可以使Ni催化剂重新活化；然而，结果突出了在Ni催化的与CO的还原偶联反应中可能出现的一个重要复杂情况。
