A novel, facile approach to frondosin B and 5-epi-liphagal via a new [4 + 3]-cycloaddition.
A new [4 + 3]-cycloaddition between benzofuran allylic alcohols and dienes, promoted by camphorsulfonic acid, has been identified. A novel strategy which used this cycloaddition as a key step has been developed for the synthesis of 6,7,5-tricyclic skeleta, and syntheses toward frondosin B (1) and 5-epi-liphagal (2) have been achieved via short routes in good yields.
State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gnasu, PR China.
Jie
J
Zhang
Liqi
L
Li
Yongxiang
Y
Wang
Wenjing
W
Wang
Jijun
J
Xue
Ying
Y
Li