A Novel Phosphorus Heterocyclic System from the Reactions of Phosphine and Primary Phosphines with 2,4-Pentanedione

Epstein, Martin; Buckler, Sheldon A.

doi:10.1021/ja01476a024

Cited by 49 publications

(29 citation statements)

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“…Other commercial reagents were used as supplied unless otherwise stated. [PtCl 2 (cod)], 19 [PdCl 2 (cod)], 20 1,3,5,7-tetramethyl-4,6,8-trioxa-2-phospha-adamantane (CgPH), 21 CgPPh, 14 Ph 2 P(2-py) 22 (L 1 ) 2-bromo-4-(trimethylsilyl)pyridine, 23 and 2-bromo-6-(trimethylsilyl)pyridine 24 were synthesised accord- General procedure for the synthesis of pyridyl-functionalised phospha-adamantyl ligands. A Schlenk flask was charged with a suspension of CgPH (1 equiv.…”

Section: General Proceduresmentioning

confidence: 99%

2-Pyridyl substituents enhance the activity of palladium–phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene

et al. 2017

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The synthesis of a series of CgPAr ligands is reported, where CgP is the 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamant-6-yl moiety and Ar = 2-pyridyl (L2), 3-pyridyl (L3), 2-pyrimidyl (L4), 4-R-2-pyridyl [R = Me (L5a), CF (L6a), SiMe (L7a)] or 6-R-2-pyridyl [R = Me (L5b), CF (L6b), SiMe (L7b). Testing of these ligands in the Pd-catalysed methoxycarbonylation of phenylacetylene reveals that the activity and branched selectivity of the catalysts derived from these ligands varies as a function of the N-heterocycle, with the catalyst derived from L5b being the most active of those tested. This, together with the poor performance of catalysts derived from L3 supports the hypothesis that the catalysis proceeds by a "proton shuttling" mechanism, an idea that previously had only been applied to arylphosphines. Reaction of [PtCl(cod)] with L where L = L2 or L4-7 yields a rac/meso mixture of the trans-[PtCl(L)] (1a-h) complexes, three of which are structurally characterised. P NMR spectroscopy shows that reaction of L3 with [PtCl(cod)] gives a mixture of mononuclear and binuclear metal complexes in solution. The complex trans-[PdCl(L2)] (4) reacts with AgBF to give the [PdCl(κ-L2)(κ-L2)]BF (5) with spectroscopic and structural characterisation confirming the presence of a P,N-chelate. H andP NMR evidence supports the assignment of a pyridyl-protonated species being formed upon treatment of 4 with TsOH·HO in CDCl; both the protonated species and chelate 5 are observed when the reaction is carried out in MeOH.

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Section: General Proceduresmentioning

confidence: 99%

2-Pyridyl substituents enhance the activity of palladium–phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene

et al. 2017

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“…The formulation of these compounds were confirmed by a combination of spectroscopic and analytical methods. [32] Furthermore, the 31 P{ 1 H} NMR chemical shifts for 1, 2a and 2b differ by ca. 10 ppm with respect to the phenyl-modified phosphaadamantanes, AdP-Ph, previously reported.…”

Section: Ligand Synthesesmentioning

confidence: 99%

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

et al. 2007

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The new nonsymmetric ditertiary phosphanes, Ph 2 PCH 2 N-(R)CH 2 PAd [3a: R = C 6 H 5 , 3b: R = C 6 H 4 (4-CH 3 )] were prepared using a three-step sequence of condensation reactions. Hence treatment of AdP-H (AdP-H = 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane) with (CH 2 O) n at 110°C gave the adamantane-derived hydroxymethylphosphane 1, which upon condensation with C 6 H 5 NH 2 or C 6 H 4 (4-CH 3 )-NH 2 gave the secondary aminophosphanes HN(R)CH 2 PAd [2a: R = C 6 H 5 , 2b: R = C 6 H 4 (4-CH 3 )]. Further condensation of 2a or 2b with Ph 2 PCH 2 OH gave 3a or 3b in high yields

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“…Although the formation of phosphatrioxaadamantanes, frequently referred to as cage phosphanes (CgPR) due to their shape, by acid‐catalyzed condensation of PH 3 and primary phosphanes with acetylacetone (Hacac) has already been reported in the 1960s, [1] ligands featuring 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphatricyclo[3.3.1.1 3,7 ]decane‐8‐yl groups (hereafter denoted as CgP; Scheme 1) and their applications emerged only decades later, [2] triggered by the discovery of reliable synthetic routes toward suitable precursors ( e. g ., CgPH, CgPH⋅BH 3 and CgPBr) [3] . Soon after, the unique characteristics of the CgP moiety were identified, including an unparalleled combination of specific steric properties, electron‐poor nature, comparable with that of a P(OR) 2 group, and high chemical robustness [2] .…”

Section: Introductionmentioning

confidence: 99%

Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C‐H Arylation of Benzoxazoles by Aryl Chlorides

2021

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Versatile applications and unique performance of 1,1’‐bis(diphenylphosphanyl)ferrocene (dppf) in coordination chemistry and catalysis prompted the search for its analogs. This contribution describes the synthesis of the first donor‐unsymmetric dppf congeners bearing bulky and rigid 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphaadamantyl (CgP) donor groups, viz. Ph2PfcPCg (1) and Ph2PfcCH2PCg (2; fc=ferrocene‐1,1’‐diyl). Bis‐phosphanes 1 and 2 were converted into air‐stable Pd(0) complexes, [Pd(ma)(L^L)] (L^L=1 and 2; ma=maleic anhydride). Together with [Pd(ma)(dppf)], these complexes were applied as catalysts in Pd‐catalyzed C−H arylation of benzoxazoles with aryl chlorides in n‐butanol as an environmentally benign solvent. Among all catalysts tested in this study, complex [Pd(ma)(2)] performed the best, providing a high‐yield and selective synthesis of 2‐arylbenzoxazoles from a range of the generally less reactive chloroarenes at low catalyst loading (typically 1 mol.%). Under similar conditions, the structurally related heterocycles (e. g., 1‐methylbenzimidazole and benzothiazole) did not react.

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A Novel Phosphorus Heterocyclic System from the Reactions of Phosphine and Primary Phosphines with 2,4-Pentanedione

Cited by 49 publications

References 0 publications

2-Pyridyl substituents enhance the activity of palladium–phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene

2-Pyridyl substituents enhance the activity of palladium–phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene

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

Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C‐H Arylation of Benzoxazoles by Aryl Chlorides

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A Novel Phosphorus Heterocyclic System from the Reactions of Phosphine and Primary Phosphines with 2,4-Pentanedione

Cited by 49 publications

References 0 publications

2-Pyridyl substituents enhance the activity of palladium–phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene

2-Pyridyl substituents enhance the activity of palladium–phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene

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

Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C‐H Arylation of Benzoxazoles by Aryl Chlorides

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