Kinetically controlled one-pot formation of DEFGH-rings of type B physalins through domino-type transformations.
The characteristic DEFGH-ring system of type B physalins has been synthesized by means of a one-pot procedure incorporating domino-type ring transformations. Unexpectedly, we found that introduction of an α-hydroxyester functionality at C17 in ring E allowed the key 7-endo oxy-Michael reaction to proceed. Originally this was thought to be an unfavored process. This afforded the desired caged ring system to be formed in a kinetically controlled manner. Consecutive treatment with AcOH at 100 °C furnished the DEFGH-ring system in one pot.
RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
Masaki
M
Morita
Go
G
Hirai
Megumi
M
Ohkubo
Hiroyuki
H
Koshino
Daisuke
D
Hashizume
Keiji
K
Maruoka
Mikiko
M
Sodeoka
D007700:Kinetics; D008968:Molecular Conformation; D012632:Secosteroids / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D012632:Secosteroids; C033270:physalin B