1629162-11-3Relevant academic research and scientific papers
Asymmetric synthesis of spiropyrazolones through phosphine-catalyzed [4+1] annulation
Han, Xiaoyu,Yao, Weijun,Wang, Tianli,Tan, Yong Ren,Yan, Ziyu,Kwiatkowski, Jacek,Lu, Yixin
, p. 5643 - 5647 (2014/06/10)
An enantioselective synthesis of spiropyrazolones from allenoate-derived MBH acetates and pyrazolones through a phosphine-mediated [4+1] annulation process has been developed. Spiropyrazolones were readily prepared in good chemical yields and good to high enantioselectivities. This is the first asymmetric example in which α-substituted allenoates were utilized as a C4 synthon for phosphine-catalyzed [4+1] annulation. Optically enriched 4-spiro-5-pyrazolones were prepared through phosphine-catalyzed enantioselective [4+1] annulation. In this study, substituted pyrazolones were used as a C1 synthon in cycloaddition for the first time. Moreover, this is the first report in which α-substituted allenoates were utilized in an asymmetric [4+1] annulation.
