title: Formal Synthesis of Solanoeclepin A: Enantioselective Allene Diboration and Intramolecular [2+2] Photocycloaddition for the Construction of the Tricyclic Core.
abstract: An enantioselective synthesis of an intermediate in the Tanino total synthesis of solanoeclepin A has been developed. The key step was an intramolecular [2+2] photocycloaddition, which led to the tricyclo[5.2.1.0(1, 6)] decane core in six steps. The first photosubstrate, prepared through an indium-mediated Barbier-type reaction, gave an excellent [2+2] cycloaddition, but it could not be obtained in sufficient enantiopurity. The second photosubstrate, prepared through an asymmetric allene diborylation in high enantiomeric excess, gave the [2+2] cycloaddition product in high yield on irradiation at 365 nm on 20 g scale in a flow system. Other important steps were the replacement of a boronate group at the quaternary carbon by a vinyl group and diastereoselective cyclopropanation of an allylic alcohol.
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands.
authors.forename: Roel A
authors.initials: RA
authors.lastname: Kleinnijenhuis
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands.
authors.forename: Brian J J
authors.initials: BJ
authors.lastname: Timmer
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands.
authors.forename: Ginger
authors.initials: G
authors.lastname: Lutteke
authors.affiliation: Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands.
authors.forename: Jan M M
authors.initials: JM
authors.lastname: Smits
authors.affiliation: Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands.
authors.forename: René
authors.initials: R
authors.lastname: de Gelder
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands.
authors.forename: Jan H
authors.initials: JH
authors.lastname: van Maarseveen
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands. h.hiemstra@uva.nl.
authors.forename: Henk
authors.initials: H
authors.lastname: Hiemstra
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D061565:Cycloaddition Reaction; D006586:Hexanes / Q000138:chemical synthesis* / Q000737:chemistry; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000466:Alkadienes; D001952:Bridged-Ring Compounds; D006586:Hexanes; D011083:Polycyclic Compounds; C431673:solanoeclepin A; C025947:propadiene
keywords: asymmetric synthesis; cycloaddition; indium; terpenoids; total synthesis