Palladium Complexes of 1,3,5,7-Tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantane:  Synthesis, Crystal Structure and Use in the Suzuki and Sonogashira Reactions and the α-Arylation of Ketones

Abstract

Palladium complexes of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantane were prepared and characterized with Pd[1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantane](2).dba shown to be an effective catalyst for use in the Suzuki and Sonogashira reactions and the alpha-arylation of ketones. Couplings using this versatile complex proceeded in excellent yields under mild conditions.

Mononuclear and Heterodinuclear Metal Complexes of Nonsymmetric Ditertiary Phosphanes Derived from R2PCH2OH

“…Given the paucity of palladium complexes with adamantane-based phosphorus ligands documented in the literature [17,19,25] we prepared the palladium(II) complex 4 by bridge cleavage of the known [34] dimeric compound {Pd(κ 2 -C,N-C 16 H 16 N)Br} 2 with 2a in refluxing acetone [Equation (1)]. Compound 4 displayed a singlet at δ(P) 18.7 ppm in the 31 P{ 1 H} NMR spectrum (Table 1) and furthermore was characterised by single-crystal X-ray crystallography.…”

“…[15,16] There has also been interest in these adamantane-based phosphane ligands for their important uses in a range of catalytic metal-mediated transformations such as aminations, hydroformylation, hydrogenations, methoxycarbonylation of internal alkenes and Suzuki and Sonogashira couplings. [17][18][19][20][21][22][23][24][25] Nonsymmetric ditertiary phosphanes have seldom been studied in relation to their symmetric counterparts possibly reflecting the necessity to perform multistep syntheses. [26][27][28][29][30][31] When considering possible coordination modes for nonsymmetric diphosphanes of the type R 2 PCH 2 XCH 2 PRЈ 2 various coordination modes are plausible some of which are shown in Figure 1.…”

Coordination Studies of a New Nonsymmetric Ditertiary Phosphane Bearing a Single Phosphaadamantane Cage

“…[15][16][17][18][19][20][21][22][23] We recently reported the synthesis and coordination studies of a new nonsymmetric ditertiary phosphane containing a P-C-N(R)-C-P skeletal backbone in which one of the P-based moieties was a phosphaadamantane cage. [24] The presence of a bulky adamantane cage imposed on this ligand the ability to adopt a range of ligating modes including κ 1 -P-monodentate coordination upon complexation to [RuCl 2 (η 6 -p-cymene)] or [IrCl 2 (η 5 -Cp*)] metal fragments.…”

Palladium‐Katalysatorsysteme für die Synthese von konjugierten Eninen durch Sonogashira‐Kupplungen und verwandte Alkinylierungen

“…Für die Alkinylierung von elektronenreichen oder sterisch gehinderten Arylbromiden erwies sich der Palladiumkomplex von 1,3,5,7-Tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantan als wirksamer Katalysator (Schema 10). [34] Capretta et al zeigten, dass Trialkylphosphan-Phosphorinane ebenfalls als Liganden für die Sonogashira-Reaktion von Arylbromiden geeignet sind (Schema 11). [35] Die Reaktionen wurden bei Raumtemperatur in Dioxan mit HNiPr 2 als Base und CuI als Cokatalysator ausgeführt.…”