Synlett 2010(1): 161-162  
DOI: 10.1055/s-0029-1218515
SPOTLIGHT
© Georg Thieme Verlag Stuttgart ˙ New York

Ytterbium Triflate: A Green Catalyst

Carina I. C. Crucho
REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
e-Mail: carinacrucho@gmail.com;
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Publikationsverlauf

Publikationsdatum:
14. Dezember 2009 (online)

Introduction

Ytterbium triflate (1) is known to be a useful mild, versatile, and environmentally friendly Lewis acid catalyst. With the ever-increasing interest in the sustainable development, Yb(OTf)3 benefits from its characteristic features: High efficiency in green media, such as water and ionic liquids, recovery after reaction completion, and reusing without loss of activity. [¹] Contrary to other Lewis acids, Yb(OTf)3 is effectively used in catalytic amounts and is widely employed in organic synthesis promoting several carbon-carbon and carbon-heteroatom bond formation, which include the aldol condensations, Mannich-type reaction, Diels-Alder cycloadditions, Friedel-Crafts acylation or alkylation, and heterocycle synthesis. [¹] Moreover, taking its advantage of the affinity to nitrogen-­containing compounds, which deactivate most Lewis ­acids, Yb(OTf)3 enhances the reactivity of the imine group and catalyses an imine ene reaction providing useful homo­allylic amines, [²] and also increases the yield of the Ugi four-component coupling. [³]