Bidentate phosphines of heteroarenes: 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene

Hillebrand, Stefan; Bruckmann, Joachim; Krüger, Carl; Haenel, Matthias W.

doi:10.1016/0040-4039(94)02206-q

Cited by 99 publications

(67 citation statements)

References 4 publications

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“…In all cases the linear product 5a was favored (product of no allylic rearrangement). The regioselectivity (product ratio 5a/6a) was the best (96:4, yield 52%) using Pd 2 (dba) 3 and xantphos ligand [66][67][68][69][70][71] (entry 6). The best regioselectivity (95:5) and yield (75%) were realized using PdCl 2 (PhCN) 2 as catalyst, for a reaction in THF at room temperature (entry 16).…”

Section: Resultsmentioning

confidence: 99%

Palladium-catalyzed desulfinylative C–C allylation of Grignard reagents and enolates using allylsulfonyl chlorides and esters

Volla¹,

Dubbaka²,

Vogel³

2009

Tetrahedron

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a b s t r a c t 2-Methylprop-2-ene-, prop-2-ene-, 1-methylprop-2-ene-, and (E)-but-2-enesulfonyl chlorides have been used as electrophilic partners in desulfinylative palladium-catalyzed C-C coupling with Grignard reagents and sodium salts of dimethyl malonate and methyl acetoacetate. Neopentyl alk-2-ene sulfonates can also be used as electrophilic partners in desulfinylative allylic arylations and allylic alkylations. The regioselectivity of the allylic arylation and alkylation depends on the nature of the catalyst. With PdCl 2 (PhCN) 2 , (E)-crotyl derivatives are formed in high regioselectivity using either 1-methylprop-2-eneor (E)-but-2-enesulfonyl chloride.

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Section: Resultsmentioning

confidence: 99%

Palladium-catalyzed desulfinylative C–C allylation of Grignard reagents and enolates using allylsulfonyl chlorides and esters

Volla¹,

Dubbaka²,

Vogel³

2009

Tetrahedron

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“…Chromatography on silica gel (MeOH/CH2Cl2, 0.75%) gave the lower-Rf, S-shaped isomer of 3 (400 mg, 35%) and the higher-Rf, C-shaped isomer of 3 (462 mg, 41%). For the C-shaped isomer: 1H NMR (250 MHz, CDCl3) 8 6.64 (br s, 2H, -NH), 4.78 (br s, 2H, -NH), 1.76 (s, 12H, Me), 1.41 (s, 18H, t-Bu), 1.32 (s, 18H, t-Bu).…”

Section: Methodsmentioning

confidence: 99%

A rigid trans-spanning dinitrile ligand.

Shimizu

Rebek

1996

Proc. Natl. Acad. Sci. U.S.A.

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(Fig. la). In contrast, functional groups such as nitriles take on a linear arrangement at nitrogen and necessitate a larger scaffold and more convergent C shape to achieve the same geometries (Fig. lb). Accordingly, multidentate nitriles are commonly oligomeric and polymeric structures and have been successfully used to assemble expansive threedimensional arrays (8,9). Chelating di-and trinitriles are also known, but they invariably bind to the same face of the metal and not to opposing faces (10)(11)(12)(13) MATERIALS AND METHODSThe C-Shaped and S-Shaped Isomers of Bisamide 3. (See Fig. 2.) A 1-to-1 mixture of C-and S-shaped isomers of diacid 2 (1.16 g, 1.17 mmol), thionyl chloride (5 ml), and four drops of N,N-dimethylformamide (DMF) were heated at reflux for 2.5 h (14). The reaction mixture was evaporated to a yellow solid under reduced pressure. The crude product was dissolved in 50 ml of CH2Cl2 and treated with 10 ml of concentrated aqueous ammonium hydroxide. The mixture was stirred vigorously for 1 h and then washed with 1.0 M HCI (twice with 100 ml), then dried over MgSO4. Chromatography on silica gel (MeOH/CH2Cl2, 0.75%) gave the lower-Rf, S-shaped isomer of 3 (400 mg, 35%) and the higher-Rf, C-shaped isomer of 3 (462 mg, 41%

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“…All hydrogen atoms and acetonitrile solvent molecules are omitted for clarity. Selected bond lengths (ä) angles, and torsion angles (8): P1 ± O1 1.6570(12); P1 ± O2 1.6512(12); P2 ± O3 1.6503(13); P2 ± O4 1.6496(12); P1 ± C1 1.8252(17); P2 ± C7 1.8290(17); O5 ± C2 1.381(2); O5 ± C8 1.378(2); P1 ± P2 4.1298(8); O1 ± P1 ± O2 99.18(6); O3 ± P2 ± O4 98.09(7); O1 ± P1 ± C1 95.89(7); O2 ± P1 ± C1 95.22(7); O3 ± P2 ± C7 97.04(7); O4 ± P2 ± C7 94.60(7); C2 ± O5 ± C8 119.33 (13); C3 ± C13 ± C9 110.34 (15); C1 ± C2 ± C3 ± C13 173.27(17); C7 ± C8 ± C9 ± C13 175.03 (17). (1)], drawn at the 50% probability level.…”

Section: Nickel(0) Complexes With Diphosphonite Ligandsmentioning

confidence: 99%

“…One of the more recent ligand systems used in homogeneous catalysis, such as hydroformylation and Pd-catalyzed C À C coupling, is based on the xanthene backbone. The diphosphine ligands derived from this rigid backbone were first described by Haenel et al [15] Independently, the group of van Leeuwen focused on various transition metal-catalyzed reactions applying these ligands. [16] The proposed strength of this class of ligands lies in the combination of a rigid backbone, the large natural bite angle, a limited number of possible coordination modes and possibly the favourable interaction of the oxygen in the backbone with the metal center.…”

Section: Introductionmentioning

confidence: 99%

Sterically Demanding Diphosphonite Ligands –Synthesis and Application in Nickel‐Catalyzed Isomerization of 2‐Methyl‐3‐Butenenitrile

et al. 2004

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Dedicated to Professor Joachim Bargon (Universit‰t Bonn) on the occasion of his 65 th birthday.Abstract: The synthesis of a novel class of sterically demanding diphosphonites 1 ± 8, based on rigid backbones, is described. The starting materials are all commercially available and the methodology allows for a modular approach. All ligands have been fully characterized, including an X-ray crystal structure for compound 1, 4,5-bis{di[(2-tert-butyl)phenyl]phosphonito}-9,9-dimethylxanthene. The coordination of these diphosphonite ligands towards Ni(II) and Ni(0) precursors is investigated, both by NMR spectroscopy as well as X-ray crystallography and compared with the behaviour of diphosphine ligands such as Xantphos. The molecular structure for complex 9, trans-[NiBr 2 (1)] is described in detail. The nickel-catalyzed isomerization of 2-methyl-3-butenenitrile to 3-pentenenitrile is studied, a relevant step in the industrially important hydrocyanation of butadiene (the DuPont adiponitrile process). Good activities and selectivities to the desired 3-pentenenitrile are obtained in this reversible C À C bond activation reaction.

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Bidentate phosphines of heteroarenes: 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene

Cited by 99 publications

References 4 publications

Palladium-catalyzed desulfinylative C–C allylation of Grignard reagents and enolates using allylsulfonyl chlorides and esters

Palladium-catalyzed desulfinylative C–C allylation of Grignard reagents and enolates using allylsulfonyl chlorides and esters

A rigid trans-spanning dinitrile ligand.

Sterically Demanding Diphosphonite Ligands –Synthesis and Application in Nickel‐Catalyzed Isomerization of 2‐Methyl‐3‐Butenenitrile

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