title: Efficient construction of alpha-spirocyclopropyl lactones: iridium-salen-catalyzed asymmetric cyclopropanation.
abstract: 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.
authors.affiliation: Department of Chemistry, Faculty of Science, Graduate School, Kyushu University, Hakozaki, Higashi-ku, Fukuoka, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Ichinose
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Suematsu
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Katsuki