Fully Reversible Cyclic Dimerization of Diphosphanylketenimines Promoted by Intramolecular C−H⋅⋅⋅N Hydrogen Bonds

Ruíz, José; Marquínez, Fernando; Vivanco, Marilín; Garcı́a-Granda, Santiago; Diaz,

doi:10.1002/(sici)1521-3773(20000515)39:10<1821::aid-anie1821>3.0.co;2-h

Cited by 22 publications

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“…Fortunately, the suitability of 3 to undergo reversible cyclic dimerization allowed us to obtain 8 in a pure form. As we have recently communicated,6 the diphosphanylketenimine 3 dimerizes upon crystallization giving the unsymmetrical dimer 6 (Scheme ), which quantitatively reverts to 3 on heating with toluene. The three trivalent phosphorus atoms in 6 can be selectively oxidized by treatment with one, two or three equivalents of H 2 O 2 giving 7, 9 , and the transient species 10 , respectively (Scheme ).…”

Section: Resultsmentioning

confidence: 85%

“…Chemical shifts are given in ppm, relative to internal SiMe 4 ( 1 H) or external 85 % H 3 PO 4 ( 31 P). The compounds 3 5 and 6 6 were prepared as described elsewhere. All other reagents were commercially obtained and used without further purification.…”

Section: Methodsmentioning

confidence: 99%

“…The new functionalized diphosphane 3 was liberated from the metallic fragment by irradiating with UV/Vis light. Compound 3 spontaneously undergoes cyclodimerization involving a phosphanyl residue upon crystallization 6. This preliminary result prompted us to investigate the reactivity of 3 as a 1,3‐dipole.…”

Section: Introductionmentioning

confidence: 99%

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Diphosphanylketenimines: New Reagents for the Synthesis of Unique Phosphorus Heterocycles

Ruiz¹,

Marquínez²,

Vivanco³

et al. 2002

Chem. Eur. J.

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Two consecutive [3+2] cycloaddition reactions of the diphosphanylketenimine (PPh2)2CCNPh (3), involving the phosphanyl groups, with two equivalents of the electron‐poor alkynes dimethyl acetylenedicarboxylate or methyl acetylenecarboxylate give rise to the formation of the bicyclic 1λ5,3λ5‐diphospholes 5 a,b, which contain a phosphorane unit with five carbon substituents attached to the phosphorus center. Compound 3 undergoes cyclodimerization by crystallization, affording the unsymmetrical dimer 6, which is converted back to 3 by heating in toluene. Compound 6 can be oxidized stepwise on the three trivalent phosphorus atoms by treatment with H2O2 affording 7, 9, and the transient species 10, which are transformed into their corresponding ketenimine monomers either spontaneously (10) or by heating in toluene (7, 9). In this way, the compound (OPPh2)(PPh2)CCNPh (8) is quantitatively obtained. Compound 8 readily reacts with the alkynes MeO2CCCCO2Me and MeO2CCCH, and with phenyl isocyanate and ethyl isothiocyanate through regiospecific [3+2] cycloaddition processes furnishing several λ5‐phosphole and λ5‐azaphosphole derivatives. Finally, the reaction of 8 with N‐methylpropargylamine yields the new 2,3‐dihydro‐1,4‐λ5‐azaphosphinine 15 through a cycloaddition process involving two functional groups from each molecule.

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Section: Resultsmentioning

confidence: 85%

Section: Methodsmentioning

confidence: 99%

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Diphosphanylketenimines: New Reagents for the Synthesis of Unique Phosphorus Heterocycles

Ruiz¹,

Marquínez²,

Vivanco³

et al. 2002

Chem. Eur. J.

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“…Reversible cyclic dimerisation of diphosphanylketenimines (Ph 2 P) 2 CNCNNPh involving a [2 + 3] cycloaddition has been observed to give an azaphospha heterocycle 14 featuring a phosphorus ylide functionality. 72 Dimerisation appears to be promoted by C-H•••N hydrogen bond formation.…”

Section: Phosphorusmentioning

confidence: 99%

Untitled

Burrows

2001

Annu. Rep. Prog. Chem., Sect. A

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“…These calculations suggest that the [NN–P] moiety of 1 could behave as a 1,3-dipole, consistent with the rapid reaction between 1 and cyclooctyne. Although 1,3-(P,C) dipole reactivity is known, − 1,3-dipolar cycloadditions involving 1,3-(P,N) dipoles are rare. In one example, Swarmy and co-workers found that the treatment of 2 equiv of azide-substituted phosphine with dipolarophile dimethylacetylene dicarboxylate (DMAD) results in the formation of a 1,3-(P,N) heterocycle containing an appended phosphazenyl azide unit …”

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An Azophosphine Synthetic Equivalent of Mesitylphosphaazide and Its 1,3-Dipolar Cycloaddition Reactions

et al. 2021

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Dibenzo-7-phosphanorbornadiene-substituted diazene MesN 2 PA (1, where Mes = mesityl, A = anthracene, or C 14 H 10 ), a synthetic equivalent of mesitylphosphaazide (MesN 2 P) and anthracene, was synthesized by treatment of [Ph 3 BPA][Na(OEt 2 ) 2 ] with [MesN 2 ]OTf (OTf = CF 3 SO 3 − ) in thawing tetrahydrofuran (14% isolated yield). Treatment of 1 with unsaturated molecules cyclooctyne, [Na(dioxane) 2.5 ][OCP] (phosphaethynolate), and Ad−CP (Ad = adamantyl) results in the corresponding [3 + 2] phosphaazide-(phospha)alkyne cycloadducts, with concomitant loss of anthracene in 65%, 49%, and 38% isolated yield, respectively. Structural data for the phosphaethynolate cycloadduct ) 2 ]) were obtained in a single-crystal X-ray diffraction study. A diazatriphosphole was generated by combining 1 with P 2 A 2 , a thermally activated anthracenebased molecular precursor to diphosphorus (P 2 ). Thermolysis (33−65 °C) of 1 in benzene-d 6 leads to anthracene extrusion. This process has a unimolecular kinetic profile and proceeds with activation parameters of ΔH ⧧ = 21.6 ± 0.3 kcal/mol and ΔS ⧧ = −4.9 ± 0.8 cal/(mol K).

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Fully Reversible Cyclic Dimerization of Diphosphanylketenimines Promoted by Intramolecular C−H⋅⋅⋅N Hydrogen Bonds

Cited by 22 publications

References 1 publication

Diphosphanylketenimines: New Reagents for the Synthesis of Unique Phosphorus Heterocycles

Diphosphanylketenimines: New Reagents for the Synthesis of Unique Phosphorus Heterocycles

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An Azophosphine Synthetic Equivalent of Mesitylphosphaazide and Its 1,3-Dipolar Cycloaddition Reactions

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