Rhodium-Catalyzed Regioselective Carboacylation of Olefins: A C—C Bond Activation Approach for Accessing Fused-Ring Systems

摘要

Efficiency in the synthesis of a complex molecular target is greatly dictated by the strategy used for building the key skeletal structure. In particular, fused rings are extremely common structural motifs in natural products and drug molecules, and thus access to these motifs through selective and atom-economic methods is of significant importance. Despite the existence of various elegant stepwise cycloaddi-tion methods for building fused-ring systems, we were particularly intrigued by a catalytic "cut-and-sew" reaction, which involves the oxidative addition of a transition metal to a C—C bond (Scheme 1). In this type of reaction, a key intermediate, for example, metallocycle B, is formed when a relatively inert C—C bond is replaced by two reactive M—C bonds, thus representing an unusual strategy for accessing complex structures that are difficult to access using conventional methods. For example, for substrates such as ketone A, regioselective cleavage of a C—C bond followed by intramolecular migratory insertion of an unsaturated moiety, such as an olefin, and reductive elimination would lead to fused-bicyclic structure C.