Transition-metal-catalyzed cycloadditions for the synthesis of eight-membered carbocycles.
Eight-membered carbocycles are found in a wide variety of natural products that exhibit a broad range of biological and medicinal activities (cf. the most potent anticancer drug, taxol). However, the synthesis of eight-membered carbocycles is quite challenging as traditional approaches are met with entropic and enthalpic penalties in the ring-forming transition states. These negative effects can be totally or partially avoided with the implementation of transition-metal-catalyzed/mediated cycloadditions. In this Focus Review, examples of elegant and efficient metal-catalyzed and some metal-mediated cycloadditions (including Ni- catalyzed [4+4] and Rh-catalyzed [4+2+2] and [5+2+1] reactions) are presented to illustrate this. Application of these cycloaddition reactions in total synthesis is also presented to show the significance of these reactions in addressing challenges in natural product synthesis.
Yu
Zhi-Xiang
ZX
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China. yuzx@pku.edu.cn
Wang
Yi
Y
Wang
Yuanyuan
Y
D002384:Catalysis; D003500:Cyclization; D034242:Cyclooctanes / Q000138:chemical synthesis* / Q000737:chemistry; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes / Q000138:chemical synthesis / Q000737:chemistry; D028561:Transition Elements / Q000737:chemistry*
D034242:Cyclooctanes; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; D028561:Transition Elements; C486985:hirsutene; C446680:hypnophilin