31989-49-8Relevant articles and documents
The synergistic copper/ppm Pd-catalyzed hydrocarboxylation of alkynes with formic acid as a CO surrogate as well as a hydrogen source: An alternative indirect utilization of CO2
Chen, Kai-Hong,He, Liang-Nian,Qiu, Li-Qi,Xia, Shu-Mei,Yang, Zhi-Wen,Yao, Xiang-Yang
supporting information, p. 8089 - 8095 (2021/11/01)
An unprecedented strategy has been developed involving the earth-abundant Cu-catalyzed hydrocarboxylation of alkynes with HCOOH to (E)-acrylic derivatives with high regio- and stereoselectivity via synergistic effects with ppm levels of a Pd catalyst. Both symmetrical and unsymmetrical alkynes bearing various functional groups were successfully hydrocarboxylated with HCOOH, and the modification of a pharmaceutical molecule exemplified the practicability of this process. This protocol employs HCOOH as both a CO surrogate and hydrogen donor with 100% atom economy and it can be viewed as an alternative approach for indirect CO2 utilization. Mechanistic investigations indicate a Cu/ppm Pd cooperative catalysis mechanism via alkenylcopper species as potential intermediates formed from Cu-hydride active catalytic species with HCOOH as a hydrogen source. This bimetallic system involving inexpensive Cu and trace Pd provides a reliable and efficient hydrocarboxylation method to access industrially useful acrylic derivatives with HCOOH as a hydrogen source, and it provides novel clues for optimizing other Cu-H-related co-catalytic systems.
Reductive elimination from metal phosphonate complexes: Circumvention of competing protonolysis reactions
Stockland Jr., Robert A.,Levine, Adam M.,Giovine, Matthew T.,Guzei, Ilia A.,Cannistra, Joseph C.
, p. 647 - 656 (2008/10/09)
The formation of MeP(O)(OPh)2 by reductive elimination from L2PdMe(P(O)(OPh)2) species has been investigated. The electronic and steric effects of the supporting ligands were investigated by studying reductive elimination reactions from a series of discrete complexes containing nitrogen- and phosphorus-based ligands. The P(O)-C(sp3) bond-forming reaction is slow when the intermediate species contains bidentate nitrogen ligands or small basic monodentate phosphines. Analogous complexes bearing large bite angle diphosphines such as dppf and Xantphos undergo reductive elimination at ambient temperature. The rate of MeP(O)(OPh)2 formation by reductive elimination from (dppf)PdMe(P(O)(OPh)2) is not affected by the identity or concentration of added ligand (excess dppf or PPh3), suggesting that the reductive elimination occurs from a four- or three-coordinate intermediate. When the rate of reductive elimination is slow, protonolysis reactions between L2PdMe(P(O)(OPh)2) intermediates and HP(O)(OPh)2 leads to the formation of bis-phosphonate complexes. The protonolysis reaction can be circumvented by the use of large bite angle phosphines such as dppf and Xantphos, which lead to rapid rates of P(O)-C(sp3) bond formation. These results demonstrate that the formation of P(O)-C(sp3) bonds by reductive elimination from L2PdRP(O)(OR)2 complexes is quite sensitive to the steric bulk of the supporting ligand and the presence of excess hydrogen phosphonate.
Lewis acids accelerate reductive elimination of RCN from P2Pd(R)(CN)
Huang, Jinkun,Haar, Christopher M.,Nolan, Steven P.,Marcone, John E.,Moloy, Kenneth G.
, p. 297 - 299 (2008/10/08)
The rate of reductive elimination of the complexes dpppPd(CH2TMS)(CNER3) (E = B, Al) is accelerated up to 60-fold over dpppPd(CH2TMS)(CN). Based on kinetic considerations and the isoelectronic relationship of CN- and CO, a migration-type mechanism for reductive elimination is proposed. The rate acceleration correlates directly with Lewis acid strength, the latter determined by solution calorimetric analyses of the Lewis acid adduct forming reaction Pd-CN + ER3 → Pd-CN-ER3.
