title: Access to a Guanacastepene and Cortistatin-Related Skeleton via Ethynyl Lactone Ireland-Claisen Rearrangement and Transannular (4 + 3)-Cycloaddition of an Azatrimethylenemethane Diyl.
abstract: Heating a 2,5-furanocyclic (2-azidoethyl)allene initiates a cascade reaction comprising azide-allene cycloaddition, loss of nitrogen, and azatrimethylenemethane (ATMM) diyl-furan transannular (4 + 3)-cycloaddition. The major product of this reaction contains the pentacyclic core common to guanacastepenes D and H and radianspenes J-L; in addition, the central oxa-bridged cycloheptene ring, flanked by two carbocyclic rings, is structurally related to the ABC-ring system found in the cortistatins. This is the first reported synthetic application of a "free" (nonconjugated) ATMM. The cyclization precursors were prepared via the first reported examples of the Ireland-Claisen rearrangement of an ethynyl lactone.
authors.affiliation: Department of Chemistry, University of Oxford , Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, U.K.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Zhurakovskyi
authors.affiliation: Department of Chemistry, University of Oxford , Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, U.K.
authors.forename: Sam R
authors.initials: SR
authors.lastname: Ellis
authors.affiliation: Department of Chemistry, University of Oxford , Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, U.K.
authors.forename: Amber L
authors.initials: AL
authors.lastname: Thompson
authors.affiliation: Department of Chemistry, University of Oxford , Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, U.K.
authors.forename: Jeremy
authors.identifier: 0000-0002-6809-8265
authors.initials: J
authors.lastname: Robertson