Control of Aldol Reaction Pathways of Enolizable Aldehydes in an Aqueous Environment with a Hyperbranched Polymeric Catalyst

Yonggui Chi, Steven T. Scroggins, Emine Boz, Jean M. J. Frechet*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

A fundamental chemoselectivity challenge that remains intrinsically unsolved in aldol-type reactions is the suppression of self-aldol reactions with enolizable aldehydes in reactions such as cross-aldol processes. Contrasting with the usual practice of using large excesses of one component to compete with the undesired self-aldehyde condensation reactions, we have developed an enzyme-like polymer catalyst consisting of a hyperbranched polyethyleneimine derivative and proline that can eliminate the self-aldol reactions by suppressing an irreversible aldol condensation pathway. Control experiments and preliminary mechanistic studies suggest that the polymer catalyst provides an optimum environment for the aldol reaction to proceed selectively in water, and the catalytic conditions provided by the polymer are difficult to duplicate with typical small molecule analogues. This polymer catalyst system or its modified version has potential applications in developing a new or more efficient synthesis, as demonstrated in a dynamic catalytic process for the preparation of a,p-unsaturated ketones using cross ketone/aldehyde reactions without the need for excess substrates.

Original languageEnglish
Pages (from-to)17287-+
Number of pages4
JournalJournal of the American Chemical Society
Volume130
Issue number51
DOIs
StatePublished - Dec 24 2008
Externally publishedYes

Keywords

  • WATER
  • ORGANOCATALYSIS
  • HYDROLYSIS

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