Expedient construction of the [5-6-7] tricyclic core of calyciphylline a-type alkaloids.
An efficient synthetic route toward the highly congested [5-6-7] tricyclic core of calyciphylline A-type alkaloids has been developed. This approach features a highly efficient intramolecular Diels-Alder cycloaddition to establish the aza-five-membered C ring as well as the C1 all-carbon quaternary center, and a subsequent cyclopropanation together with a ring-expansion reaction of the resulted adduct to construct the seven-membered D ring.
Department of Chemistry, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000 (P. R. China).
Jing-Jing
JJ
Guo
Yun
Y
Li
Bin
B
Cheng
Tingting
T
Xu
Cheng
C
Tao
Xinkan
X
Yang
Denghong
D
Zhang
Guangqi
G
Yan
Hongbin
H
Zhai
Diels-Alder; calyciphylline A-type; daphniphyllum alkaloids; natural products; ring expansion