title: Stereoselective Synthesis of the Taxane Ring System via the Tandem Diels-Alder Cycloaddition.
abstract: The application of the tandem Diels-Alder cycloaddition to the stereoselective synthesis of the tricyclic ring system of the taxane diterpenes is described. The exceedingly direct, two-step synthesis of the B/C cis-fused taxane nucleus in 50% overall yield from the reaction of two readily available acyclic precursors underscores the efficiency of this approach. A critical feature of the second, intramolecular Diels-Alder cyclcoaddition is the transmission of stereochemical information across the taxane framework, i.e., from the C ring to the A ring. The cycloaddition of both cis- and trans-disubstituted C ring constructs leads to the establishment of the requisite C-1/C-3 relative stereochemistry for the synthesis of taxanes. A computational model is presented to account for the high levels of asymmetric induction observed in these reactions.
authors.affiliation: Department of Chemistry, The University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095.
authors.forename: Jeffrey D.
authors.initials: JD
authors.lastname: Winkler
authors.forename: Hak Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Sanghee
authors.initials: S
authors.lastname: Kim
authors.forename: Kaori
authors.initials: K
authors.lastname: Ando
authors.forename: Kendall N.
authors.initials: KN
authors.lastname: Houk