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)-H functionalization reactions of 4-aryl-5-pyrazolones followed by 3+2 annulation reactions with alkynes provide rapid access to highly enantioenriched five-membered-ring 4-spiro-5-pyrazolones. The use of a chiral SCpRh catalyst enabled the synthesis of a large range of spiropyrazolones with all-carbon quaternary stereogenic centers in up to 99 % yield and 98 % ee from readily available substrates.
Zheng et al. (2017) studied this question.