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Unexpected Activation of Ethers and Polysiloxanes by a Phosphine-Borane-Stabilized 1,3-Dicarbanion/Butyllithium Couple

Lookup NU author(s): Dr Keith Izod, Dr Paul Waddell

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society, 2019.

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Abstract

The reaction between the tertiary phosphine-borane PhP(BH3)(CH2Ph)2 (6) and one equivalent of nBuLi, PhCH2Na, or PhCH2K gives the mono-deprotonation products [PhP(BH3)(CHPh)(CH2Ph)]MLn (MLn = Li(OEt2)0.25 (7), Na(THF)0.5 (8), K(OEt2)0.5 (9)). Similarly, the reaction between 6 and two equivalents of either PhCH2Na, or PhCH2K gives the 1,3-dicarbanion complexes [PhP(BH3)(CHPh)2][MLn]2 (MLn = Na(THF) (10), K(THF)0.25 (11)). However, the reaction between 6 and two equivalents of nBuLi in Et2O, THF, or nBu2O gives a mixture of mono- and di-metalated products. Unexpectedly, the reaction between 6 and three equivalents of nBuLi in diethyl ether in the presence of silicone grease gives the trinuclear cluster [PhP(BH3)(CHPh)2]Li3(OSiMe2CH2CH2CH2CH3)(OEt2)3 (12); this compound may be isolated in essentially quantitative yield from the reaction between 6, hexamethyltrisiloxane and nBuLi in a 3:1:9 ratio. Similar tri-lithium complexes are isolated from the reaction between 6 and three equivalents of nBuLi in Et2O or tBuOMe, which yield [PhP(BH3)(CHPh)2]Li3(OEt)(OEt2)3 (13) and [PhP(BH3)(CHPh)2]Li3(OMe)(OtBuMe)3 (14), respectively. The reaction between 6, two equivalents of nBuLi and one equivalent of in situ generated LiOEt or LiOiPr, gave the tri-lithium clusters 13 and [PhP(BH3)(CHPh)2]Li3(OiPr)(OEt2)3 (16), respectively.


Publication metadata

Author(s): Izod K, Madlool AM, Waddell PG

Publication type: Article

Publication status: Published

Journal: Organometallics

Year: 2019

Volume: 38

Issue: 13

Pages: 2654-2663

Print publication date: 08/07/2019

Online publication date: 20/06/2019

Acceptance date: 05/06/2019

Date deposited: 11/06/2019

ISSN (print): 0276-7333

ISSN (electronic): 1520-6041

Publisher: American Chemical Society

URL: https://doi.org/10.1021/acs.organomet.9b00236

DOI: 10.1021/acs.organomet.9b00236


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