Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate, which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers, which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent ef-fects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

Automated summary

Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate that can be activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain. The nature of C1-substituent in unsymmetrical OBDs has a profound effect on the reactivity and selectivity of reactions, leading to the formation of multiple stereo-, regio-, and constitutional isomers. Understanding bridgehead substituent effects is crucial for maximizing selectivity in the chemistry of unsymmetrical C1-substituted OBDs.