Synlett 2008(7): 1103-1104  
DOI: 10.1055/s-2008-1066996
SPOTLIGHT
© Georg Thieme Verlag Stuttgart · New York

MagtrieveTM (CrO2): A Versatile Oxidant in Organic Synthesis

Yu-Heng Liu*
The College of Chemistry & Materials Science, Hebei Normal University, Shijiazhuang 050016, P. R. of China
e-Mail: liu2795478@yahoo.com.cn;
Further Information

Publication History

Publication Date:
17 March 2008 (online)

Introduction

Magtrieve is a magnetically retrievable oxidant based on tetravalent chromium dioxide (CrO2). [1] It is a selective, heterogeneous form of CrO2, whose reduced form stays on the crystal surface. It is insoluble in most common organic solvents. Reactions with MagtrieveTM are typically performed in chlorinated solvents or toluene. Magtrieve has found wide application in organic synthesis, such as in the oxidation of allylic alcohols to allylic aldehydes, [2] the formation of benzyl from benzoin, [3] the aromatization of imidazolines, [4] the conversion of 2-hydroxymethyl-6,7- bis(pentylsulfanyl)tetrathiafulvalene into 2-formyl-6,7- bis(pentylsulfanyl) tetrathiafulvalene, [5] oxidation of 2-methoxyphenols to 1,4-benzoquinones, [6] etc. This reagent is still ferromagenetic and can be conveniently removed after the reaction by a simple magnetic separation, because only the surface of the CrO2 is reduced. This has significant environmental and cost advantages over traditional chromium reagents that require aqueous work-up and consequent appropriate disposal of the chromium waste. In addition, the reduced chromium surface can be simply reconverted into CrO2 by heating in air, thus adding to its recyclability and cost-effectiveness. Magtrieve as an oxidant is a very well-suited reagent for microwave synthesis because it carries the benefit of efficient conversion of electromagnetic energy into heat according to the dielectric heating mechanism. [7]

    References

  • 1 Lee RA. Donald DS. Tetrahedron Lett.  1997,  38:  3857 
  • 2 Vincent F. Widger WR. Openshaw M. Gaskell SJ. Kohn H. Biochemistry  2000,  39:  9067 
  • 3 Crumbie RL. J. Chem. Educ.  2006,  83:  268 
  • 4 de la Hoz A. Díaz-Ortiz Á. del Carmen Mateo M. Moral M. Moreno A. Elguero J. Foces-Foces C. Rodríguez ML. Sánchez-Migallóna A. Tetrahedron  2006,  62:  5868 
  • 5 Hudhomme P. Sallé M. Gautier N. Belyasmine A. Gorgues A. ARKIVOC  2006,  (iv):  49 
  • 6 Jacob AM. Moody CJ. Tetrahedron Lett.  2005,  46:  8823 
  • 7 Bogdal D. Lukasiewicz M. Pielichowski J. Miciak A. Bednarz S. Tetrahedron  2003,  59:  649 
  • 8 Sun Y.-H. Ko K.-Y. Bull. Korean Chem. Soc.  2000,  21:  665 
  • 9 Ko K.-Y. Kim J.-Y. Bull. Korean Chem. Soc.  1999,  20:  771 
  • 10 Park S.-T. Ko K.-Y. Bull. Korean Chem. Soc.  2002,  23:  367 
  • 11 Ko K.-Y. Park S.-T. Tetrahedron Lett.  1999,  40:  6025 
  • 12 Lukasiewicz M. Bogdal D. Pielichowski J. Adv. Synth. Catal.  2003,  345:  1269 
  • 13 Ko K.-Y. Kim J.-Y. Tetrahedron Lett.  1999,  40:  3207