Angular dependence of phosphorane and ylide formation

Turnblom, E. Wayne; Katz, Thomas J.

doi:10.1039/c3972001270b

Cited by 6 publications

(3 citation statements)

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“…4,6,[19][20][21][22] Pentaalkylation of the phosphonium center in a [PR 4 ] + cation is only possible in systems where the corresponding ylides suffer from configurational or conformational strain, or if strain already present in a phosphonium cation is reduced or relieved upon changes in the coordination sphere of the phosphorus atom. 23 Two polycyclic phosphonium salts have been designed for these purposes (focusing on the latter of the two principles) and yielded the first and only examples of true pentaalkylphosphoranes.…”

Section: Introductionmentioning

confidence: 99%

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5-Organyl-5-phosphaspiro[4.4]nonanes: A Contribution to the Structural Chemistry of Spirocyclic Tetraalkylphosphonium Salts and Pentaalkylphosphoranes

et al. 2002

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Spirocyclic phosphonium salts of the type [(CH(2))(4)P(CH(2))(4)](+) X(-) with X = I(3) (1a), I (1b), picrate (1c), benzoate (1d), and Cl (1e) were prepared from 1,4-diiodobutane and elemental phosphorus followed by metathesis reactions. The crystal structures of 1b and 1c and of 1d(H(2)O) have been determined by X-ray diffraction methods. In the cations of these salts the phosphorus atoms are shared by two five-membered rings in envelop conformations. In the picrate 1c the cations show an unsymmetrical ring folding pattern (point group C(1)), while the geometry of the cations of the iodide 1b and the benzoate hydrate [1d(H(2)O)] approaches the symmetry of point group C(2). These structures can be taken as models for the as yet unknown molecular geometries of the corresponding hydrocarbon (CH(2))(4)C(CH(2))(4) and silane (CH(2))(4)Si(CH(2))(4). Treatment of 1e with organolithium reagents RLi affords spirocyclic pentaorganophosphoranes RP[(CH(2))(4)](2) with R = Me, Et, n-Bu, Vi, and Ph (2a-e) in good (R = Me, Et, n-Bu) to low yields (R = Vi, Ph). The products are isolated as colorless liquids, of which only 2a, 2b, and 2d can be distilled without decomposition. Single crystals of 2a were obtained by low-temperature in situ crystal growth. The molecule has a trigonal bipyramidal configuration with the methyl group in an equatorial position and the two five-membered rings spanning axial/equatorial positions of the polyhedron. Deviations from the standard trigonal bipyramidal geometry are small. The compounds 2a-e are fluctional in solution as demonstrated by NMR spectroscopy.

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Section: Introductionmentioning

confidence: 99%

“…Penta alkyl ation of the phosphonium center in a [PR 4 ] + cation is only possible in systems where the corresponding ylides suffer from configurational or conformational strain, or if strain already present in a phosphonium cation is reduced or relieved upon changes in the coordination sphere of the phosphorus atom …”

Section: Introductionmentioning

confidence: 99%

5-Organyl-5-phosphaspiro[4.4]nonanes: A Contribution to the Structural Chemistry of Spirocyclic Tetraalkylphosphonium Salts and Pentaalkylphosphoranes

et al. 2002

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“…271 The effectiveness of Si2CI6 in reduction of a few anglestrained phosphine oxides 451 and 452 has been reported. 201,336,338 The simple system (f? )-(+)-benzylmethylphenylphosphine oxide also gave the corresponding phosphine with inverted configuration.274…”

Section: Reductionmentioning

confidence: 99%