Divergent Total Syntheses of (−)‐Daphnilongeranin B and (−)‐Daphenylline. Issue 4 (5th December 2017)

• Record Type: Journal Article
• Authors: Chen, Xiaoming; Zhang, Hai‐Jun; Yang, Xinkan; Lv, Houqiang; Shao, Xiaoru; Tao, Cheng; Wang, Huifei; Cheng, Bin; Li, Yun; Guo, Jingjing; Zhang, Jing; Zhai, Hongbin
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 4(2018)
• Page Start: 947
• Page End: 951
• Publication Date: 2017-12-05
• Subjects: alkaloids -- asymmetric total synthesis -- [3+2] cycloaddition -- natural products -- rearrangement; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201709762
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: (−)‐Daphnilongeranin B and (−)‐daphenylline are two hexacyclic Daphniphyllum alkaloids, each containing a complex cagelike backbone. Described herein are the first asymmetric total synthesis of (−)‐daphnilongeranin B and a bioinspired synthesis of (−)‐daphenylline with an unusual E ring embedded in a cagelike framework. The key features include an intermolecular [3+2] cycloaddition, a late‐stage aldol cyclization to install the F ring of daphnilongeranin B, and a bioinspired cationic rearrangement leading to the tetrasubstituted benzene ring of daphenylline. Abstract : Two of a kind : The hexacyclic Daphniphyllum alkaloids (−)‐daphnilongeranin B and (−)‐daphenylline were synthesized from a common pentacyclic intermediate (see scheme). The key features of the syntheses included an intermolecular [3+2] cyclization, a late‐stage aldol cyclization to install the cyclopentenone ring of daphnilongeranin B, and a bioinspired cationic rearrangement leading to the tetrasubstituted benzene ring of daphenylline.