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Microwave-Assisted Ester Formation Using O-Alkylisoureas: A Convenient Method for the Synthesis of Esters with Inversion of Configuration

Research output: Contribution to journalLiterature review

  • Alessandra Chighine
  • Stefano Crosignani
  • Marie-Claire Arnal
  • Mark Bradley
  • Bruno Linclau

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Original languageEnglish
Pages (from-to)4753-4762
Number of pages10
JournalJournal of Organic Chemistry
Volume74
Issue number13
DOIs
Publication statusPublished - 3 Jul 2009

Abstract

The formation of carboxylic esters via reaction of carboxylic acids with O-alkylisoureas proceeds in excellent yields with very short reaction times when conducted in a monomode microwave synthesizer. Efficient processes were developed using preformed or commercially available isoureas derived from primary and secondary alcohols, with a reaction time of only 5 min or less. It was demonstrated that under these microwave conditions, ester formation proceeded in good yields with clean inversion of configuration where appropriate. The process was validated using menthol, a hindered substrate for S(N)2 reactions. In addition, starting from primary alcohols, ester formation was successfully accomplished using ail in situ isourea formation procedure. A polymer-assisted solution-phase procedure was also developed by employing preformed solid-supported isoureas and by an efficient "catch and release" ester formation procedure whereby primary alcohols were caught on resin as isoureas by reaction with immobilized carbodiimide and released as esters by subsequent treatment with a carboxylic acids.

    Research areas

  • SOLID-SUPPORTED REAGENTS, CONTINUOUS-FLOW CONDITIONS, SOLUTION-PHASE SYNTHESIS, SOLVENT-FREE CONDITIONS, ONE-POT CONVERSION, ZARAGOZIC-ACID-A, CARBOXYLIC-ACIDS, MITSUNOBU REACTION, ORGANIC-SYNTHESIS, NATURAL-PRODUCTS

ID: 1480110