Unusual manganese(III)-mediated oxidative free-radical additions of Meldrum's acid and dimethyl malonate to benzonorbornadiene and oxabenzonorbornadiene

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 effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

Efficient syntheses and antimicrobial activities of new thiophene containing pyranone and quinolinone derivatives using manganese(iii) acetate: the effect of thiophene on ring closure–opening reactions

The syntheses, spectroscopic properties, and antimicrobial activities of new pyranones and quinoline-based dihydrofurans accompanied by 3-alkenyl-substituted structures were investigated.