N,N′ and N,O chelated phosphenium cations containing aminotroponiminate or aminotroponate units

Pop, Lucian Cristian; Katir, Nadia; Castel, Annie; Silaghi‐Dumitrescu, Luminiţa; Delpech, Fabien; Silaghi‐Dumitrescu, Ioan; MacLeod‐Carey, Desmond; Saffon, Nathalie

doi:10.1016/j.jorganchem.2009.01.022

Cited by 11 publications

(8 citation statements)

References 35 publications

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“…Its molecular structure (including selected bond lengths and angles) is shown in Figure 2. Compound 4 shows the same general features as phosphenium cation 1 11 consisting of separated ion‐pairs with triflate as the anion. The nearest distance between the ions is F – ··· H(cation) (2.73 Å).…”

Section: Resultsmentioning

confidence: 88%

“…In previous work,11 we have shown the impact of the synthetic process on the nature of the product obtained when phosphorus bears an aminotroponiminato substituent. Indeed, the nucleophilic substitution reaction of PCl 3 and the monolithiated ligand gave a mixture of dissociated and non‐dissociated forms 1a and 1b whereas the base‐induced dehydrochlorination coupling reaction selectively yielded the phosphenium cation 1a (Scheme ).…”

Section: Resultsmentioning

confidence: 98%

“…DFT calculations were performed on phosphenium11 and arsenium cations 20. They revealed a high‐lying phosphorus lone‐pair orbital (HOMO–1) which should allow an easy coordination of phosphenium cations to metal carbonyl fragments.…”

Section: Resultsmentioning

confidence: 99%

“…Surprisingly, only a few Group 15 element complexes of this type have been described,8 whereas a large number of intermolecular donor adducts of both phosphenium3a,9 and arsenium10 cations are known. As part of our ongoing investigation of main‐group elements in unusually low oxidation states, we have recently shown that chlorophosphenium cations can be stabilized by aminotroponiminate and aminotroponate ligands 11. In this paper, we report an extension of this work to the N,N‐ and N,O‐chelated stabilization of the arsenic element.…”

Section: Introductionmentioning

confidence: 81%

“…Elemental analyses were performed at the Centre de Microanalyse de l'Ecole Nationale Supérieure des Ingénieurs en Arts Chimiques et Technologiques. N ‐Isopropyl‐2‐(isopropylamino)troponimine, 2‐(isopropylamino)tropone30 and the phosphenium cation 1a 11 were prepared according to literature procedures. The atom labelling used in the NMR assignments of 2 is given below: …”

Section: Methodsmentioning

confidence: 99%

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Aminotroponiminate and Aminotroponate Complexes of Group 15 (P, As) Elements: Synthesis, X‐ray Diffraction Analysis and Reactivity

et al. 2011

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New phosphenium and arsenium cations stabilized by bidentate monoanionic N-isopropyl-2-(isopropylamino)troponiminate or 2-(isopropylamino)troponate units have been synthesized. These complexes were characterized by 31 P, 1 H and 13 C NMR spectroscopy and the molecular structures were determined by X-ray crystallography. These data indicate the formation of N,NЈ-and N,O-chelate derivatives with threecoordinate Group 15 atoms included in planar heterobi-

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 81%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Aminotroponiminate and Aminotroponate Complexes of Group 15 (P, As) Elements: Synthesis, X‐ray Diffraction Analysis and Reactivity

et al. 2011

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Asymmetric Organocatalytic Electrophilic Phosphination

2011

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Asymmetric Organocatalytic Electrophilic Phosphination

2011

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The asymmetric incorporation of phosphorus-containing groups into target molecules is an important goal in diverse areas of synthetic chemistry. Organophosphorus compounds are used in various fields such as the synthesis of natural products [1] and their analogues, [2] ligands in organometallic catalysis, [3] organocatalysis, [4] and in general synthetic chemistry.[5] Hence, the development of asymmetric organocatalytic approaches towards optically active organophosphorus molecules is highly important.[6] A synthetic limitation is that previously the asymmetric catalytic formation of stereogenic carbon centers bonded to phosphorus (C*ÀP) has only been performed using nucleophilic phosphorus compounds. [7] Herein we present the first asymmetric catalytic C*ÀP bond formation employing a phosphine electrophile. By reacting asubstituted cyanoacetates (1) [8] with diaryl phosphine chlorides (2) under organocatalytic conditions, [9] optically active a-phosphinated cyanoacetates (3), which contain a stereogenic quaternary carbon center, are obtained (Scheme 1).Furthermore, 3 is transformed into protected chiral aquaternary a-phosphino b-amino acids [10] (4) by using a onepot procedure. This class of compounds might also be regarded as precursors for novel P,N ligands.[3f]Initially, we focused on the formation of a-phosphinated cyanoacetates (3), in which an equivalent of HCl is produced during the course of the reaction. Previously, phase-transfer catalysis (PTC) has been shown to be a useful protocol for this type of reaction.[11] However, several attempts using PTC failed to produce any traceable amounts of 3.[12] We therefore turned our attention to the use of cinchona alkaloids. Pleasingly, using a stoichiometric amount of (DHQD) 2 PYR (5 ; Table 1) led to a 77 % conversion within 30 minutes under ambient reaction conditions. However, only traces of 3 were formed when 0.1 equivalent of 5 was employed, which was attributed to the protonation of the catalyst. We anticipated that this problem could be solved by employing a base capable of scavenging the acid. Indeed, the addition of an excess of proton sponge (1,8-bis(dimethylamino)naphthalene) [13] when using 10 mol % of 5 led to full conversion after 6 hours under ambient reaction conditions.Having established a catalytic system, extensive screening [12] resulted in the development of the reaction shown in Table 1, in which step a with subsequent oxidative protection of the phosphine (step b), nitrile reduction, and then N protection (step c), [14] provided highly enantioenriched 4 (up to 93 % ee) in good yields (> 85 % for each reaction step). The scope of this reaction was studied by carrying out a range of reactions, in which both the R and the ester substituents in 1, and the aryl substituents in 2 were varied (Table 1). All the yields reported in Table 1 are for the formation of 4 from 1, and are thus the result of four steps performed in a one-pot fashion.Initially, it was shown that employing either (DHQD) 2 PYR (5) or (DHQ) 2 PYR (dihydroquinine 2,5-diphenyl...

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N,N′ and N,O chelated phosphenium cations containing aminotroponiminate or aminotroponate units

Cited by 11 publications

References 35 publications

Aminotroponiminate and Aminotroponate Complexes of Group 15 (P, As) Elements: Synthesis, X‐ray Diffraction Analysis and Reactivity

Aminotroponiminate and Aminotroponate Complexes of Group 15 (P, As) Elements: Synthesis, X‐ray Diffraction Analysis and Reactivity

Asymmetric Organocatalytic Electrophilic Phosphination

Asymmetric Organocatalytic Electrophilic Phosphination

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