Lithium bis(2‐phenylphosphidoethyl)phenyl‐phosphine: A reactive phosphorus intermediate

Abstract

Bis(2‐phenylphosphinoethyl)phenylphosphine, PhP(CH2CH2PPh2)2, reacts with lithium in tetrahydrofuran to give the corresponding lithium bis(2‐diphenylphosphidoethyl)phenylphosphine, Li2[PhP(CH2CH2PPh)2]. The lithium diphosphide is identified by NMR spectroscopy and further characterized through arylation with excess brombenzene to reform the starting phosphine, PhP(CH2CH2PPh2)2. Initial reactivity studies of the diphosphide, PhP(CH2CH2PPh), with some alkylhalides are also described. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:675–678, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20351

The Quest for Twofold Reductive P–C Bond Cleavage of P–Ph Substituted 1,4‐Dihydro‐1,4‐diphosphinine Derivatives

“…Alkali metal‐induced reductive cleavage of P–C bonds, in tertiary phosphanes has become an important methodology in synthetic chemistry since its first report by Gilman in 1958 . The products of this reaction, i.e., the secondary phosphanides are key intermediates for the synthesis of a wide range of secondary and tertiary designer phosphanes . Regarding the case of asymmetrically substituted tertiary phosphanes such as compounds I (Figureà) in which more than one P–C bond can be reductively cleaved, the synthetic importance of the reaction solely depends on the selectivity of the reductive cleavage .…”

Nitrogen, phosphorus, arsenic, antimony and bismuth

“…47 Reaction of PhP(CH 2 CH 2 PPh 2 ) 2 with lithium results in the generation of the bis-phosphide PhP(CH 2 CH 2 PPh) 2 Li 2 and LiPh, quenching with alkyl halides provided a route to novel tripodal phosphine ligands. 48 A radical promoted substitution of phosphines Me 3 MPPh 2 (M = Si or Sn) by organohalide RX has been reported. 49 A series of crystalline phosphorus compounds containing non-stoichiometric amounts of a P(III) (P-lone pair) and P(v) (PQO) species have been investigated.…”

Preparation of Diphenyl Phosphide and Substituted Phosphines using Alkali Metal in Silica Gel (M−SG)

“…Understanding the factors controlling selectivity in the cleavage of alkyldiarylphosphines may allow design and control of stereochemistry and redox potentials of organometallic complexes . Such reactions have been studied but mostly in the context of P-arylated bisphosphines with varying spacers. − For cleavage of the simpler butyldiphenylphosphine, we find nearly exclusive dearylation to form butyl phenyl phosphide (Scheme ). This result seems sensible in terms of the relative stabilities of phenyl vs butyl carbanion salts (p K a (R−H) ∼ 43 and 50, respectively), assuming they are formed directly in the cleavage.…”

“…42 Such reactions have been studied 43 but mostly in the context of P-arylated bisphosphines with varying spacers. [44][45][46][47][48][49] For cleavage of the simpler butyldiphenylphosphine, we find nearly exclusive dearylation to form butyl phenyl phosphide (Scheme 2). This result seems sensible in terms of the relative stabilities of phenyl vs butyl carbanion salts (pK a (R-H) ∼ 43 and 50, respectively 50 ), assuming they are formed directly in the cleavage.…”