Samarium and Ytterbium Reagents

Abstract

In contrast to more traditional organometallic nucleophiles, the application of samarium and ytterbium reagents to selective organic synthesis has a relatively brief history. Early studies of lanthanide reagents simply sought to develop reactivity patterns mimicking those of more established organolithium or Grignard reagents. However, as the complexity of organic molecules requiring synthesis increased, demands for more highly selective reagents heightened accordingly. Consequently, the search for reagents which would complement those of the traditional organometallic nucleophiles brought more serious attention to the lanthanides, and an explosive expansion in the application of lanthanide reagents to organic synthesis began. This growth is perhaps best reflected by the publication of a number of excellent review articles. 1 In addition, quite thorough surveys on the synthetic and structural aspects of organolanthanide chemistry have appeared. 2 This chapter concentrates on applications of samarium and ytterbium reagents in selective organic synthesis, and specifically their employment in C X π-bond addition reactions. Emphasis is placed on transformations that are unique to the lanthanides, and on processes that complement existing synthetic methods utilizing more traditional organometallic reagents. Since additions to C X π-bonds comprise one of the most essential aspects of carbon–carbon bond formation, fundamental contributions made in this area are by definition of substantial importance to the art of organic synthesis.