Synlett 2005(20): 3169-3170  
DOI: 10.1055/s-2005-922755
SPOTLIGHT
© Georg Thieme Verlag Stuttgart · New York

Dirhodium Tetraacetate: An Effective Catalyst in Organic Synthesis

Pranab Haldar*
Department of Chemistry, Indian Institute of Technology, ­Kharagpur 721302, India
e-Mail: pranab@chemist.com;
Further Information

Publication History

Publication Date:
28 November 2005 (online)

Introduction

Unlike free carbenes, Rh(II)-catalyzed carbenoids often undergo highly regio- and stereoselective intra- and intermolecular insertion into a sigma bond. Although many transition-metal complexes afford carbenoids, only those of Rh(II) have shown general applicability due to their higher selectivity. The pioneering development of Rh(II) acetate by Teyssie and co-workers [1] has resulted in highly chemo-, regio- and stereoselective reactions of α-diazocarbonyl compounds via a variety of reactivity modes. Subsequently, an extensive library of successful transformations rapidly evolved, ranging from Rh(II)-catalyzed OH [2] and NH [3] insertion to cyclopropanation of olefins [4] and aromatic systems. [5]

Rh(II)-catalyzed reactions can often be performed in the presence of water. Because of the high partition of Rh2(OAc)4 in the water phase, the catalyst can be effectively reused, [6] permitting the development of a more environmentally benign process. Dirhodium tetraacetate is conveniently prepared by refluxing RhCl3·3H2O and sodium acetate/acetic acid in ethanol and is now also commercially available. The Rh2(OAc)4 core has approximately D 4h symmetry, with the Lewis base adducts H2O in 1 coordinating to the sites trans to the Rh-Rh bond.