Experimentation du plan de synthese etabli avec l'aide de pascop

Villien, Luc; Kaufmann, G.

doi:10.1016/s0040-4020(01)96892-9

Cited by 8 publications

(2 citation statements)

References 22 publications

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“…The intermediate generated on deprotonation of the SPO appears to be best described as a phosphinite anion because of the 31 P{ 1 H} NMR chemical shift from 55.8 ppm (diisopropylphosphine oxide) to 121.6 ppm (Figure , R = i Pr) in THF . The phosphinite anion prefers P–C bond formation over O–C bond formation, with the exception of oxophilic electrophiles such as chlorosilanes (which is in good agreement with observations in the literature). , This observation suggests that the hard oxygen nucleophile is cation passivated and only attacks strongly oxophilic substrates. In all cases reported here, bond formation was observed at the phosphorus exclusively.…”

Section: Resultssupporting

confidence: 86%

“…37 The phosphinite anion prefers P−C bond formation over O−C bond formation, with the exception of oxophilic electrophiles such as chlorosilanes (which is in good agreement with observations in the literature). 49,50 This observation suggests that the hard oxygen nucleophile is cation passivated and only attacks strongly oxophilic substrates. In all cases reported here, bond formation was observed at the phosphorus exclusively.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

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Improved Synthetic Route to Heteroleptic Alkylphosphine Oxides

2017

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A new method for the synthesis of heteroleptic alkylphosphine oxides (R 2 R 1 PO, where R ≠ R 1 ) from secondary phosphine oxides (or SPOs, R 2 HPO) is presented. These reactions were fast at room temperature, sterically selective, high yielding, and >95% pure after an aqueous wash. Deprotonation of an SPO generates a phosphinite anion ([R 2 P− O] − ) that was found to be highly selective for nucleophilic P−C bond formation (as opposed to O−C bond formation) with alkyl halides. Surprisingly, most strong organometallic bases failed to deprotonate SPOs to their respective phosphinite anions (pK a s for most SPOs are <27). Only sodium bis(trimethylsilyl)amide (NaHMDS) cleanly formed the phosphinite anion, which was stable in solution (0.1 M, 23 °C in THF) for over 24 h. The need for a very specific base to deprotonate suggests that both ion pairing and the conjugate acid play a role in stabilizing the phosphinite anion. Phosphinite anion reactivity followed the expected trend for an S N 2 mechanism on reaction with alkyl halides; elimination products were never observed. A wide variety of heteroleptic alkylphosphine oxides were isolated in near-quantitative yield with only an aqueous wash as purification. This methodology was then used to make new bis(phosphine oxide)alkanes and unsymmetrical α,ω-bis(phosphine oxide)alkanes (R 2 P(O)(CH 2 ) 3 P(O)R 12 ) on the benchtop with unprecedented ease.

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Section: Resultssupporting

confidence: 86%