Catalytic Asymmetric[4+1]Spiroannulation ofα-Bromo-βNaphthols with Azoalkenes by an Electrophilic Dearomatization/S_(RN)1-Debromination Approach  

作　　者：Lu Bai Xin Luo Yicong Ge Hui Wang Jingjing Liu Yaoyu Wang Xinjun Luan 

机构地区：[1]Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education,College of Chemistry&Materials Science,Northwest University,Xi’an 710127 [2]State Key Laboratory of Elemento-Organic Chemistry,Nankai University,Tianjin 300071

出　　处：《CCS Chemistry》2022年第3期1054-1064,共11页中国化学会会刊（英文）

基　　金：supported by the National Natural Science Foundation of China(nos.21925108 and 21901203);the Key Science and Technology Innovation Team of Shaanxi(no.2017KCT-37);the Key Laboratory Project of Xi’an(no.201805058ZD9CG42);the Education Department of Shaanxi Province(nos.18JS108 and 20JK0934).

摘　　要：An enantioselective[4+1]spiroannulation ofαbromo-β-naphthols with azoalkenes has been developed for the one-step construction of a new class of pyrazoline-based spirocyclic molecules.Using chiral Cu(II)/Box catalysts,asymmetric induction was achieved with high levels of enantioselectivity[up to 99:1 enantiomeric ratio(er)].Notably,α-chloroandα-iodo-substitutedβ-naphthols were also tolerated by this reaction.Mechanistic studies disclosed that this process was triggered by electrophilefacilitated dearomatization ofα-bromo-β-naphthols and followed by the debromination via SRN 1-subsitution with in situ-formed N-nucleophile.The chiral copper(II)-species,bound with azoalkene moiety,was assumed to control the enantiodiscrimination over the naphthoxy C-radical that was generated from the debromination step.Moreover,the potential utility of this protocol was greatly amplified by the derivatization of spirocyclic products through oxidative dearomatization of the other aromatic ring in the naphthyl fragment,providing a rather attractive route for the rapid generation of synthetically more valuable doubly dearomatized architectures.

关 键 词：DEAROMATIZATION spiroannulation bromonaphthol azoalkene asymmetric catalysis 

分 类 号：O62[理学—有机化学]