Quaternary Carbon Center Forming Formal [3 + 3] Cycloaddition Reaction via Bifunctional Catalysis: Asymmetric Synthesis of Spirocyclohexene Pyrazolones Jin-Yu Liu Jing Zhao Jia-Lu Zhang Peng-Fei Xu 10.1021/acs.orglett.7b00610.s001 https://acs.figshare.com/articles/journal_contribution/Quaternary_Carbon_Center_Forming_Formal_3_3_Cycloaddition_Reaction_via_Bifunctional_Catalysis_Asymmetric_Synthesis_of_Spirocyclohexene_Pyrazolones/4787620 A variety of spirocyclohexene pyrazolones were synthesized in good yields with excellent stereoselectivities through an asymmetric, intermolecular, quaternary carbon center forming [3 + 3] cycloaddition reaction catalyzed by a bifunctional catalyst. The vinylogous pyrazolones used as binucleophilic synthons in this reaction exhibited superior ability for constructing pyrazolone related spirocyclic scaffolds. 2017-03-24 19:06:14 vinylogous pyrazolones spirocyclic scaffolds Spirocyclohexene Pyrazolones quaternary carbon center Asymmetric Synthesis spirocyclohexene pyrazolones binucleophilic synthons Bifunctional Catalysis bifunctional catalyst