Oxidative Cycloaddition And Enantioselective 1,4-Addition Based On Quinone Intermediates

Quinones are one of the most important synthons in organic synthesis due to their dearomatized property and high electrophilicity.However,the notable tendency of hydrolysis and dimerization impeded the application of analogous labile quinone compounds.To circumvent the instability and isolation issue,we realized the in situ generation of labile quinone intermediates by applying hemin/H₂O₂ as a biomimetic catalytic oxidation system,and reported their 1,3-dipolar cycloaddition with N-aryl hydrazones for the first time.It renders a novel and efficient one-step intermolecular assembly of 1,3,4-oxadiazines,which overcame the limitations of multistep synthesis and features the easy availability of the catalyst,oxidant,and substrates as well as high step and atom economy,ease of handling,and mild conditions.Besides,we successfully prepared a new type of 1,2-indolequinone compound from indole precursor and firstly achieved an enantioselective 1,4-addition with nucleophilic indoles catalyzed by the chiral phosphoric acid,affording the centrally chiral enol derivatives stabilized by the intermolecular hydrogen-bond with high enantioselectivities.We deeply explored the chirality transfer process during the tautomerization as well,and realized the construction of axially chiral bisindole derivatives.It furtherly increased our understanding of quinone reactivities,and provided a significant guidance for the coming research relevant to indolequinone compounds.