Tandem Synthesis of Enantioenriched Spirolactones via One-Pot Heck-Matsuda Reactions Directly from Nitroarenes

We report herein a novel, efficient, and expeditious approach for enantioselective intramolecular carbonylative Heck-Matsuda reaction, employing highly accessible, stable, and cost-effective nitroarenes as masked electrophiles. This tandem process combines the one-pot reduction of nitroarenes to the respective anilines, diazotization, Heck-Matsuda, carbonylation, and cyclization, enabling the synthesis of enantioenriched spirolactones. The method achieves overall yields of up to 76% with excellent enantiomeric ratios of up to 96:4 under mild conditions. Isotopically labeled products are readily obtained with near stoichiometric 13C carbon monoxide. Importantly, nitroarenes are used as masked electrophiles, which serve as an advantageous alternative to anilines and aryldiazonium salts for the Heck-Matsuda reaction. This approach thereby avoids the isolation of sensitive aryldiazonium salt intermediates and, consequently, the dangers associated with them. Density Functional Theory (DFT) calculations provide precise insights into the enantioenrichment mechanism, highlighting the significance of Pd carbonyl complexes for efficient diastereoconvergence. Microkinetic modeling of the computationally obtained reaction network results in an enantioenrichment of sub-kcal-accuracy in comparison to the experiment. This work not only showcases the level of complexity achievable in the field of tandem reactions but also highlights the utility of nitroarenes in complex organic transformations, demonstrating their potential for both academic and industrial applications.