Synlett 2010(12): 1880-1881  
DOI: 10.1055/s-0030-1258101
SPOTLIGHT
© Georg Thieme Verlag Stuttgart ˙ New York

Ytterbium Trifluoromethansulfonate

Tran Anh Tuan*
Laboratoire de Chimie Organique Multifonctionnelle, Institut de Chimie Moléculaire et des Matériaux d’Orsay, 91405 Orsay, France
e-Mail: tuanchimieorganique@yahoo.fr;
Further Information

Publication History

Publication Date:
30 June 2010 (online)

Introduction

Ytterbium trifluoromethansulfonate [Yb(OTf)3] has been widely used in organic syntheses in the last few years. [¹] Yb(OTf)3 is a strong Lewis acid [²] due to the hard character of Yb³+ ion and the presence of electron-deficient triflate in its coordination sphere. In contrast to traditional Lewis acids, such as AlCl3, BF3, TiCl4, and SnCl4, which are often used in stoichiometric amounts, only catalytic amounts of Yb(OTf)3 are necessary. Moreover it can be easily recovered and reused without loss of activity. Interestingly, Yb(OTf)3 remains catalytically active in the presence of many Lewis bases containing nitrogen, oxygen, phosphorus or sulfur atoms. The resulting water-compatibility of Yb(OTf)3 [³] is one of its well-known advantages, with respect to traditional Lewis acids that are very sensitive and easily decomposed or deactivated in the presence of small amounts of water. The most interesting point from a synthetic point of view is that Yb(OTf)3-catalyzed reactions are clean, while Yb(OTf)3 is regarded as environmentally friendly catalyst. Ytterbium triflate is prepared by heating ytterbium(III) oxide or chloride in an aqueous trifluoromethansulfonic acid solution (Scheme 1). [4] [5]

Scheme 1

This reagent has been used in numerous organic transformations, [¹] e.g. in aldol reactions, [6] Kharasch-type additions, [7] glycosylations, [8] Friedel-Crafts acylations, [9] dealkoxyacetylations, [¹0] syntheses of β-enaminones, [¹¹] etc. This article describes some major applications in organic synthesis in the recent years.