Mixed alkylamido aluminate as a kinetically controlled base

Hiroshi Naka, James V. Morey, Joanna Haywood, Dana J. Eisler, Mary McPartlin, Felipe García, Hironaga Kudo, Yoshinori Kondo, Masanobu Uchiyama, Andrew E.H. Wheatley

研究成果: Article査読

66 被引用数 (Scopus)

抄録

The mechanisms by which directed ortho metalation (DoM) and postmetalation processes occur when aromatic compounds are treated with mixed alkylamido aluminate i-Bu3Al(TMP)Li (TMP-aluminate 1; TMP = 2,2,6,6- tetramethylpiperidide) have been investigated by computation and X-ray diffraction. Sequential reaction of ArC(=O)N(i-Pr)2 (Ar = phenyl, 1-naphthyl) with t-BuLi and i-Bu3Al in tetrahydrofuran affords [2-(i-Bu3Al)CmHnC(=O)N(i-Pr) 2]Li·3THF (m = 6, n = 4, 7; m = 10, n = 6, 8). These data advance the structural evidence for ortho-aluminated functionalized aromatics and represent model intermediates in DoM chemistry. Both 7 and 8 are found to resist reaction with HTMP, suggesting that ortho-aluminated aromatics are incapable of exhibiting stepwise deprotonative reactivity of the type recently shown to pertain to the related field of ortho zincation chemistry. Density functional theory calculations corroborate this view and reveal the existence of substantial kinetic barriers both to one-step alkyl exchange and to amido-alkyl exchange after an initial amido deprotonation reaction by aluminate bases. Rationalization of this dichotomy comes from an evaluation of the inherent Lewis acidities of the Al and Zn centers. As a representative synthetic application of this high kinetic reactivity of the TMP-aluminate, the highly regioselective deprotonative functionalization of unsymmetrical ketones both under mild conditions and at elevated temperatures is also presented.

本文言語English
ページ(範囲)16193-16200
ページ数8
ジャーナルJournal of the American Chemical Society
130
48
DOI
出版ステータスPublished - 2008 12月 3

ASJC Scopus subject areas

  • 触媒
  • 化学 (全般)
  • 生化学
  • コロイド化学および表面化学

フィンガープリント

「Mixed alkylamido aluminate as a kinetically controlled base」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル