离子液体参与反应综述

A novel liquid-phase strategy for organic synthesis using organic ions as soluble supports

Congde Huo a and Tak Hang Chan*b

Received 20th November 2009

First published as an Advance Article on the web 17th May 2010DOI:10.1039/b914497h

This critical review describes a new liquid-phase strategy for organic synthesis by using organic ions as soluble supports.Catalysts or reagents or substrates are immobilized onto organic ions.They are generally soluble in polar organic solvents (e.g.CH 3CN)or ionic liquids but insoluble in non-polar solvents (e.g.ether or hexanes).Their reactions are carried out in homogeneous

solution phase with a polar organic solvent or ionic liquid.After the reaction,the ion-supported species can be phase separated through precipitation from the polar organic solvent by the

addition of a less polar organic solvent or extraction with organic solvents from ionic liquids.The ion-supported species can therefore be easily recovered and purified from the reaction mixture by simple washings with the less polar solvent.The ion-tagged species can function in the role of a catalyst,or as a reagent,or as the substrate in the synthesis of small molecules or bio-oligomers.Ion-supported catalysts and reagents can usually be recovered and reused with little diminution of activity.Important biooligomers such as peptides,oligosaccharides and oligonucleotides have been synthesized with this method (136references).

1.Introduction

1.1

Solid-vs.liquid-phase organic synthesis

Organic reactions are usually carried out in the solution phase.After completion of the reaction,phase separation between the

organic and aqueous phase is usually performed to remove water-soluble inorganics in the aqueous phase.The organic product together with the reagents and any side products are then recovered from the organic phase and purified by various means.In 1963,functionalized cross-linked insoluble solid polymer resin as support was first introduced by Merrifield for peptide synthesis.1Solid-phase organic synthesis has developed enormously since then.2,3Solid-phase synthesis has been highly successful mainly because the product can be easily separated from the reagents by simple filtration.The process is readily automated for biopolymer synthesis and now

Key Laboratory of Eco-Environment-Related Polymer Materials,Ministry of Education,China.Gansu Key Laboratory of Polymer Materials,College of Chemistry and Chemical Engineering,Northwest Normal University,Lanzhou,Gansu 730070,China.E-mail:huocongde1978@ b

Department of Chemistry,McGill University,Montreal,Quebec,Canada H3A 2K6.E-mail:

tak-hang.chan@macgill.ca

Congde Huo

Dr Congde Huo obtained his BA (2000)and PhD (2005)from Lanzhou University (supervisor Zhong-Li Liu)in China.He was then a post-doctoral fellow at the Hong Kong Polytechnic University (2005–2007)and McGill University (2007–2009)under the supervision of Prof.Tak-Hang Chan.In autumn 2009,He joined Northwest Normal University as an Associate Professor of chemistry.His research interests lie in green chemistry,radical cation chemistry and medicinal

chemistry.

Tak Hang Chan

Prof.Chan received his BSc (Toronto)in 1962,MSc (Princeton)in 1963and PhD (Princeton)in 1965under the supervision of R.K.Hill.He was Research Associate in Harvard University,1965–1966,under the super-vision of R.B.Woodward.He then joined McGill University in 1966,and is currently Professor Emeritus.He is also the Distinguished Chair Professor of Organic Chemistry in the Hong Kong Polytechnic University.His research inter-est.covers the development of novel reactions in environmentally clean solvents such as water or ionic liquids.The second area of research is in medicinal chemistry.In collaboration with biological scientists,compounds with anticancer,anti-bacterial or antiviral activities are synthesized and evaluated in terms of their structure–activity relationship and mechanism of action.

CRITICAL REVIEW /csr |Chemical Society Reviews