32647-84-0Relevant academic research and scientific papers
Origins of Regioselectivity in Iridium Catalyzed Allylic Substitution
Madrahimov, Sherzod T.,Li, Qian,Sharma, Ankit,Hartwig, John F.
, p. 14968 - 14981 (2015)
Detailed studies on the origin of the regioselectivity for formation of branched products over linear products have been conducted with complexes containing the achiral triphenylphosphite ligand. The combination of iridium and P(OPh)3 was the first catalytic system shown to give high regioselectivity for the branched product with iridium and among the most selective for forming branched products among any combination of metal and ligand. We have shown the active catalyst to be generated from [Ir(COD)Cl]2 and P(OPh)3 by cyclometalation of the phenyl group on the ligand and have shown such species to be the resting state of the catalyst. A series of allyliridium complexes ligated by the resulting P,C ligand have been generated and shown to be competent intermediates in the catalytic system. We have assessed the potential impact of charge, metal-iridium bond length, and stability of terminal vs internal alkenes generated by attack at the branched and terminal positions of the allyl ligand, respectively. These factors do not distinguish the regioselectivity for attack on allyliridium complexes from that for attack on allylpalladium complexes. Instead, detailed computational studies suggest that a series of weak, attractive, noncovalent interactions, including interactions of H-bond acceptors with a vinyl C - H bond of the alkene ligand, favor formation of the branched product with the iridium catalyst. This conclusion underscores the importance of considering attractive interactions, as well as repulsive steric interactions, when seeking to rationalize selectivities.
Iridium complexes of orthometalated triaryl phosphites: Synthesis, structure, reactivity, and use as imine hydrogenation catalysts
Bedford, Robin B.,Castillòn, Sergio,Chaloner, Penny A.,Claver, Carmen,Fernandez, Elena,Hitchcock, Peter B.,Ruiz, Aurora
, p. 3990 - 3997 (2008/10/08)
Di-orthometalated iridium complexes of triaryl phosphites have been prepared and characterized. The synthesis of the triphenyl phosphite derivative [IrH(cod){P(OC6H4)2-(OC6H 5)}], 3, requires a circuitous route by treatment of [IrCl(cod){P(OPh)3}] with methyllithium and then methanol. However, with the hindered phosphites P(OAr)3 (Ar = C6H4-2-tBu or C6H3-2,4-tBu2) the di-orthometalated species 5a,b are readily obtained by reaction of the phosphite with [{Ir(μ-OMe)(cod)}2] or [Ir(cod)(py)2][PF6]. The mechanisms of these reactions have been investigated and are different. Both 5a and 5b are catalysts for imine hydrogenation. The complexes [IrH5{P(OAr)3}2] have been isolated from hydrogenation reactions and synthesized independently.
The Synthesis and Single-crystal X-Ray Structure of the First Example of a Tridentate, Di-orthometallated Triphenyl Phosphite Complex
Bedford, Robin B.,Chaloner, Penny A.,Hitchcock, Peter B.
, p. 2049 - 2050 (2007/10/02)
Reaction of with triphenyl phosphite leads to the previously reported complex >, but reaction of Cl> with methyllithium and subsequent treatment with methanol yields the tridentate di-orthometallated complex >.
