Palladium(0)-Catalyzed Allylic Aminations: Kinetics and Mechanism of the Reaction of Secondary Amines with Cationic [(3
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- 作者：Christian Amatore ; Emilie Gé ; nin ; Anny Jutand ; Laure Mensah
- 刊名：Organometallics
- 出版年：2007
- 出版时间：April 9, 2007
- 年：2007
- 卷：26
- 期：8
- 页码：1875 - 1880
- 全文大小：134K
- 年卷期：v.26,no.8(April 9, 2007)
- ISSN：1520-6041
文摘
The mechanism of the reaction of secondary amines (piperidine, morpholine) with the cationic complexes[(
BORDER=0 >3-PhCHCHCHR)PdL2]+BF4- (R = Ph, L = PPh3 or L2 = dppb; R = H, L2 = dppb) has beeninvestigated in DMF. The reaction, which affords the tertiary allylic amine, is irreversible when L is amonodentate ligand such as PPh3, whereas the reaction is reversible when L2 is a bidentate ligand suchas dppb. In all cases, piperidine is more reactive than morpholine. The rate and equilibrium constantshave been determined in DMF. These results can be combined with our previous results on the mechanismof the reversible formation of cationic [(3-PhCHCHCHPh)PdL2]+AcO- by reacting Pd0L2 complexeswith (E)-PhCH=CHCH(Ph)OAc. Fully established catalytic cycles are now proposed for the Pd-catalyzedallylic amination of (E)-PhCH=CHCH(Ph)OAc by piperidine and morpholine. The amine and AcO- arein competition in their reaction with the cationic complexes [(3-PhCHCHCHPh)PdL2]+. The nucleophilicattack of the amine may be faster than the attack of AcO- and thus limited by the ionization step inwhich [(3-PhCHCHCHPh)PdL2]+ is formed, this ionization step being turnover limiting for the catalyticcycle.
BORDER=0 >3-PhCHCHCHR)PdL2]+BF4- (R = Ph, L = PPh3 or L2 = dppb; R = H, L2 = dppb) has beeninvestigated in DMF. The reaction, which affords the tertiary allylic amine, is irreversible when L is amonodentate ligand such as PPh3, whereas the reaction is reversible when L2 is a bidentate ligand suchas dppb. In all cases, piperidine is more reactive than morpholine. The rate and equilibrium constantshave been determined in DMF. These results can be combined with our previous results on the mechanismof the reversible formation of cationic [(3-PhCHCHCHPh)PdL2]+AcO- by reacting Pd0L2 complexeswith (E)-PhCH=CHCH(Ph)OAc. Fully established catalytic cycles are now proposed for the Pd-catalyzedallylic amination of (E)-PhCH=CHCH(Ph)OAc by piperidine and morpholine. The amine and AcO- arein competition in their reaction with the cationic complexes [(3-PhCHCHCHPh)PdL2]+. The nucleophilicattack of the amine may be faster than the attack of AcO- and thus limited by the ionization step inwhich [(3-PhCHCHCHPh)PdL2]+ is formed, this ionization step being turnover limiting for the catalyticcycle.