Efficient construction of alpha-spirocyclopropyl lactones: iridium-salen-catalyzed asymmetric cyclopropanation.
Three- and seven-membered rings were constructed by the title reaction of terminal olefins with vinyldiazolactone as a carbene source, the seven-membered rings upon subsequent hydrolysis and Cope rearrangement when 1,3-dienes were used (see example). The alpha-spirocyclopropyl lactones were formed with high E (trans) selectivity and high enantioselectivity, and cyclopropanation occurred at the terminal double bond in 1,3-dienes with excellent regioselectivity.
Ichinose
Masami
M
Department of Chemistry, Faculty of Science, Graduate School, Kyushu University, Hakozaki, Higashi-ku, Fukuoka, Japan.
Suematsu
Hidehiro
H
Katsuki
Tsutomu
T