title: Identification of an Unexpected 2-Oxonia[3,3]sigmatropic Rearrangement/Aldol Pathway in the Formation of Oxacyclic Rings. Total Synthesis of (+)-Aspergillin PZ.
abstract: This paper reports the first unambiguous evidence that the cascade synthesis of tetrahydrofuran-containing oxacyclic molecules depicted in Scheme 12 can take place by a 2-oxonia[3,3]sigmatropic/aldol mechanism rather than by a Prins cyclization/pinacol rearrangement sequence. The 8-oxabicyclo[3.2.1]octyl aldehyde products of this reaction, 20 and 29, were employed to complete the first total synthesis of the structurally remarkable isoindolone alkaloid (+)-aspergillin PZ (1). The lack of activity seen in two tumor cell lines for synthetic (+)-aspergillin PZ calls into question the suggestion that aspergillin PZ, like many aspochalasin diterpenes, might exhibit useful antitumor properties.
authors.affiliation: Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, CA 92697-2025.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Canham
authors.forename: Larry E
authors.initials: LE
authors.lastname: Overman
authors.forename: Paul S
authors.initials: PS
authors.lastname: Tanis