Directed Lithiation of Pentadienylsilanes

Benjamin M. Day, Joseph J W McDouall, Jonathan Clayden, Richard A. Layfield*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

4 Citations (Scopus)

Abstract

Deprotonation of dimethyl(pyrrolidylmethyl)silylpentadiene (5) and bis(2-methoxyethyl)aminomethyl(dimethyl)silylpentadiene (7) with <sup>n</sup>BuLi/tmeda and <sup>n</sup>BuLi, respectively, results in their corresponding lithium complexes, 6 and 8. The lithium cation in 6 is coordinated by an η<sup>1</sup>-pentadienyl ligand via the α-carbon and by the pendant pyrrolidyl group. The lithium cation in 8 is η<sup>2</sup> coordinated by the pentadienyl α- and β-carbons and by the bis(methoxyethyl)amino group. The structure of 6 is retained in benzene solution, but in thf the tmeda coligand is displaced by the solvent. A 3.5:1 mixture of the W- and S-conformations of the pentadienyl carbons was observed for 8 in benzene. DFT calculations of NBO charges for the pentadienyl carbons in 6 and 8 show that lithium polarizes the electron density toward the α-carbon, although a series of electrophile quenching reactions with 6 show that regioselectivity does not depend on the electronic structure of the pentadienyl carbanion.

Original languageEnglish
Pages (from-to)2348-2355
Number of pages8
JournalOrganometallics
Volume34
Issue number11
Early online date14 Jan 2015
DOIs
Publication statusPublished - 8 Jun 2015

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    Day, B. M., McDouall, J. J. W., Clayden, J., & Layfield, R. A. (2015). Directed Lithiation of Pentadienylsilanes. Organometallics, 34(11), 2348-2355. https://doi.org/10.1021/om501144f