Chiral Palladium(0)trans-Stilbene Complexes:  Synthesis, Structure, and Oxidative Addition of Phenyl Iodide

Abstract

The chiral Pd(0) trans-stilbene complexes Pd(diphos*)(trans-stilbene) (diphos* = (R,R)-Me-Duphos, (R,R)-Et-Duphos, (R,R)-i-Pr-Duphos, (R,R)-Me-BPE, (S,S)-Me-FerroLANE, (S,S)-Me-DuXantphos, (S,S)-Et-FerroTANE, (R,S)-CyPF-t-Bu, (R,S)-PPF-t-Bu, (R,S)-BoPhoz) and Ni((R,R)-Me-Duphos)(trans-stilbene) were prepared by NaBH(OMe)3 reduction of the corresponding M(diphos*)Cl2 compounds in the presence of trans-stilbene. The rate of oxidative addition of phenyl iodide to the stilbene complexes, which gave Pd(diphos*)(Ph)(I), depended on the ligand (larger for increased ligand bite angles and reduced steric bulk) and was markedly faster than oxidative addition to mixtures of Pd(dba)2 and diphos*. The complexes Pd(diphos*)(Ph)(I) were prepared independently by treatment of PdL2(Ph)(I) (L2 = TMEDA, (PPh3)2) with diphos*. Oxidative addition of PhI to the complexes M((R,R)-Me-Duphos)(trans-stilbene) occurred in the rate order Pd > Ni ≫ Pt. The complexes Pd(diphos*)Cl2, Pd(diphos*)(trans-stilbene), and Pd(diphos*)(Ph)(I), as well as some analogous Ni compounds, were structurally characterized by X-ray crystallography.

Resting State and Elementary Steps of the Coupling of Aryl Halides with Thiols Catalyzed by Alkylbisphosphine Complexes of Palladium

“…Dinuclear palladium(0) dba complex 9 was generated independently as a complex mixture of isomers in 39% yield by allowing (CyPF- t Bu)Pd(dba)34 to react with NaO t Bu and isopropylamine for 3 h at 100 °C. A related binuclear bisphosphine-palladium complex of dba, [(BINAP)Pd] 2 (dba), has been isolated and reported to be precatalyst for the palladium-catalyzed amination of aryl halides 35…”

“…To do so, the reaction of Pd(CyPF- t Bu)[S(C 6 H 4 -4-OMe)] 2 ( 7 ) with trans -stilbene to form the Pd(0) complex [Pd(CyPF- t Bu)( trans -stilbene)] ( 15 )34 was examined (eq 11). The oxidative addition of bis(4-methoxyphenyl) disulfide to stilbene complex 15 was complete at room temperature in less than 1 h. In contrast, treatment of Pd(CyPF- t Bu)[S(C 6 H 4 -4-OMe)] 2 ( 7 ) with trans -stilbene at 100 °C for prolonged times (>24 h) did not consume the bis-thiolate complex.…”

Electrochemistry and complexation of Josiphos ligands

“…In the asymmetric complexes, [2PdBrPh] and [2PdIPh], the differences were 0.131 and 0.1151 Å respectively; the difference in P-Pd bond lengths was attributes to the stronger trans-influence of phenyl as compared to the halide [29,43]. Somewhat surprisingly, the P-Pd distances are not significantly different (0.00085 Å ) in the related symmetric complex, [2Pd(g 2 -trans-stilbene)] [43]. The geometry about the palladium can be described as distorted square planar.…”

Selective formation of a C3-symmetric P-stereogenic tris(phosphine) via platinum-catalyzed asymmetric alkylation of a tris(secondary phosphine)

“…Mass spectrometry was performed at the University of Illinois. Reagents were from commercial suppliers, except for compounds Pt(Me-DuPhos)(Ph)(Cl) 26 and MeC(CH2PHPh)3 1, 6 which were synthesized using literature procedures.…”