title: Diastereoselective multicomponent cascade reaction leading to [3.2.0]-heterobicyclic compounds.
abstract: A general three-component triple cascade reaction through an iminium-enamine-iminium sequential activation initiated by a hetero-Michael addition to α,β-unsaturated aldehydes affords [3.2.0]heterobicycles in high diastereoselectivity. The rate and diastereoselectivity of the reaction depended on the (E)-4-heterocrotonate and size of the secondary amine. The enantiomers of the major diastereoisomer of oxa- and azabicyclo[3.2.0]heptane derivatives were separated by enzymatic kinetic resolution with immobilized  Candida antarctica  Lipase B (CALB), with E values up to 153. The absolute configuration of the nonacylated enantiomer of oxabicyclo[3.2.0]heptane was determined by single crystal X-ray analysis.
authors.affiliation: Faculty of Science, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Kerti
authors.initials: K
authors.lastname: Ausmees
authors.forename: Kadri
authors.initials: K
authors.lastname: Kriis
authors.forename: Tõnis
authors.initials: T
authors.lastname: Pehk
authors.forename: Franz
authors.initials: F
authors.lastname: Werner
authors.forename: Ivar
authors.initials: I
authors.lastname: Järving
authors.forename: Margus
authors.initials: M
authors.lastname: Lopp
authors.forename: Tõnis
authors.initials: T
authors.lastname: Kanger