190141-83-4Relevant academic research and scientific papers
P-Alkynyl functionalized benzazaphospholes as transmetalating agents
Zhou, Daniel Y.,Miura-Akagi, Preston M.,McCarty, Sierra M.,Guiles, Celeste H.,O'Donnell, Timothy J.,Yoshida, Wesley Y.,Krause, Colleen E.,Rheingold, Arnold L.,Hughes, Russell P.,Cain, Matthew F.
supporting information, p. 599 - 611 (2021/01/28)
Exposure of 10π-electron benzazaphosphole 1 to HCl, followed by nucleophilic substitution with the Grignard reagent BrMgCCPh afforded alkynyl functionalized 3 featuring an exocyclic -CC-Ph group with an elongated P-C bond (1.7932(19) ?). Stoichiometric experiments revealed that treatment of trans-Pd(PEt3)2(Ar)(i) (Ar = p-Me (C) or p-F (D)) with 3 generated trans-Pd(PEt3)2(Ar)(CCPh) (Ar = p-Me (E) or p-F (F)), 5, which is the result of ligand exchange between P-I byproduct 4 and C/D, and the reductively eliminated product (Ar-CC-Ph). Cyclic voltammetry studies showed and independent investigations confirmed 4 is also susceptible to redox processes including bimetallic oxidative addition to Pd(0) to give Pd(i) dimer 6-Pd2-(P(t-Bu)3)2 and reduction to diphosphine 7. During catalysis, we hypothesized that this unwanted reactivity could be circumvented by employing a source of fluoride as an additive. This was demonstrated by conducting a Sonogashira-type reaction between 1-iodotoluene and 3 in the presence of 10 mol% Na2PdCl4, 20 mol% P(t-Bu)Cy2, and 5 equiv. of tetramethylammonium fluoride (TMAF), resulting in turnover and the isolation of Ph-CC-(o-Tol) as the major product.
Preparation and properties of trans-Pd(Ar) (C≡CPh) (PEt3)2. Intermolecular alkynyl ligand transfer between copper(I) and palladium(II) complexes relevant to palladium complex catalyzed cross-coupling of terminal alkyne with haloarene in the presence of CuI cocatalyst
Osakada, Kohtaro,Sakata, Reiko,Yamamoto, Takakazu
, p. 5354 - 5364 (2008/10/08)
trans-Pd(C6H4Me-p)(I)(PEt3)2 (2a) reacts with [Cu(C≡CPh)(PPh3)]4 (Pd:Cu = 1:1) at room temperature to give the cross-coupling product PhC≡CC6H4Me-P (3a) in 74% yield. Reactions of 2a with [Cu(C≡CPh)(PPh3)I4 at -30 °C as well as of trans-Pd(C6H4X-P)(I)(PEt3)2 (2a, X = Me; 2b, X = OMe; 2c, X = F) with the alkynylcopper complex and additional PPh3 (2 mol/ mol of Cu) at room temperature give mixtures of PhC≡CC6H4X-P (3a, X = Me; 3b, X = OMe; 3c, X = F) and trans-Pd(C6H4X-P)(C≡CPh)(PEt3) 2 (4a, X = Me; 4b, X = OMe; 4c, X = F). Complexes 4a,b have been isolated from the latter reaction mixtures and fully characterized. Pd-C(alkynyl) and Pd-C(aryl) bond distances in 4a are 2.016(8) and 2.062(7) A, respectively. Addition of Cul to a solution of 4a at room temperature causes complete conversion of 4a into 2a and 3a in 1 h. The relative molar ratio between 2a and 4a after reaction for 2 h varies, depending on the amount of added PPh3. Reactions of trans-Pt(C6H4X-p)(I)(PEt3)2 (5b, X = OMe; 5c, X = F) with [Cu(C≡CPh)(PPh3)]4 at room temperature afford trans-Pt(C6H4X-p)(C≡CPh)(PEt3) 2 (6b, X = OMe; 6c, X = F), respectively. Heating an equimolar mixture of 4a and 5b at 35-50 °C leads to inter-metal exchange of the alkynyl and iodo ligands, giving 2a and 6b quantitatively. The reaction follows the kinetics that is first order in concentration of 4a and in that of 5b. The kinetic parameters are obtained as ΔH? = 110 kJ mol-1, ΔS? = -58 J mol-1 deg-1, and ΔG? = 127 kJ mol-1 at 298 K. The alkynyl ligand migration from Pd(II) to Pt(II) is enhanced by addition of a catalytic amount of CuI.
Intermolecular alkynyl-ligand migration from aryl-palladium(II) to -platinum(II) complexes with and without a CuI catalyst. Reversible transfer of the alkynyl group between copper(I) and palladium(II) complexes
Osakada, Kohtaro,Sakata, Reiko,Yamamoto, Takakazu
, p. 1265 - 1266 (2007/10/03)
Alkynyl-ligand transfer from [PdR(OCPh)L2] (R = C6H4Me-p, L = PEt3) to [PtR′(I)L2] (R′ = C6H4OMe-p), to give [PdR(I)L2] and [PtR′(GCPh)L2], has been enhanced to a large extent by addition of CuI, indicating reversible ligand transfer between PdII and CuI complexes.
