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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Formal Asymmetric Synthesis of (-)-Cephalotaxine, (-)-Cephalotine B and (-)-Fortuneicyclidin A/B
Qing-Kang Zhang1,2, Xi-Zhan Zan1,2, Yi-Fu Zhang1,2
1School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, P. R. China.
Abstract:
Asymmetric Stevens rearrangement of chiral aza-quaternary ammonium salts, synthesized from Weinreb amides using alkyl triflates, enables efficient construction of the chiral quaternary carbon centers. This method, featuring subsequent functional group transformations, allows for the concise asymmetric synthesis of (-)-cephalotaxine, (-)-cephalotine B, (-)-fortuneicyclidin A, and (-)-fortuneicyclidin B. This study enables a more concise and efficient implementation of the asymmetric Stevens rearrangement, thereby facilitating its application in the asymmetric synthesis of complex alkaloid molecules.
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