Origin of Fast Catalysis in Allylic Amination Reactions Catalyzed by Pd-Ti Heterobimetallic Complexes.
Experiments and density functional calculations were used to quantify the impact of the Pd--Ti interaction in the cationic heterobimetallic ClTi(NBuPPh)Pd(η³-methallyl) catalyst 1 used for allylic aminations. The catalytic significance of the Pd--Ti interaction was evaluated computationally by exami...
| Publicado en: | Journal of the American Chemical Society Vol. 137; no. 23; pp. 7371 - 7379 |
|---|---|
| Autores principales: | , , , , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
6/17/2015
|
| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=108388962&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 108388962 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 6/17/2015 vid: 137 iid: 23 pid: 997 pub: American Chemical Society artinfo: ui: 108388962 10.1021/jacs.5b02428 ppf: 7371 ppct: 8 formats: tig: atl: Origin of Fast Catalysis in Allylic Amination Reactions Catalyzed by Pd-Ti Heterobimetallic Complexes. aug: au: Walker, Whitney K. Kay, Benjamin M. Michaelis, Scott A. Anderson, Diana L. Smith, Stacey J. Ess, Daniel H. Michaelis, David J. affil: Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, United States su: Heterobimetallic complexes Allylic amination Metal complexes Organic synthesis Catalysis sug: subj: Heterobimetallic complexes Allylic amination Metal complexes Organic synthesis Catalysis ab: Experiments and density functional calculations were used to quantify the impact of the Pd--Ti interaction in the cationic heterobimetallic ClTi(NBuPPh)Pd(η³-methallyl) catalyst 1 used for allylic aminations. The catalytic significance of the Pd--Ti interaction was evaluated computationally by examining the catalytic cycle for catalyst 1 with a conformation where the Pd--Ti interaction is intact versus one where the Pd--Ti interaction is severed. Studies were also _oo_ '-- performed on the relative reactivity of the cationic monometallic (CH)(NBuPPh)Pd(η³-methallyl) catalyst 2 where the Ti from catalyst 1 was replaced by an ethylene group. These computational and experimental studies revealed that the Pd--Ti interaction lowers the activation barrier for turnover-limiting amine reductive addition and accelerates catalysis up to 10. The Pd--Ti distance in 1 is the result of the N'Bu groups enforcing a boat conformation that brings the two metals into close proximity, especially in the transition state. The turnover frequency of classic Pd π allyl complexes was compared to that of 1 to determine the impact of P--Pd--P coordination angle and ligand electronic properties on catalysis. These experiments identified that cationic (PPh)Pd(η³-CHC(CH)CH) catalyst 3 performs similarly to 1 for allylic aminations with diethylamine. However, computations and experiment reveal that the apparent similarity in reactivity is due to very fast reaction kinetics. The higher reactivity of 1 versus 3 was confirmed in the reaction of methallyl chloride and 2,2,6,6-tetramethylpiperidine (TMP). Overall, experiments and calculations demonstrate that the Pd--Ti interaction induces and is responsible for significantly lower barriers and faster catalysis for allylic aminations. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2015 holdings: @attributes: islocal: N |
|---|