title: Bicyclic- and tricyclic-beta-lactones via organonucleophile-promoted bis-cyclizations of keto acids: Enantioselective synthesis of (+)-dihydroplakevulin.
abstract: A highly diastereoselective, nucleophile-promoted bis-cyclization process, employing readily available and tractable keto acid substrates, is described. This methodology provides concise access to bicyclic- and tricyclic-beta-lactones bearing tertiary carbinol centers and quaternary carbons, greatly extending the scope of previous routes to bicyclic-beta-lactones from aldehyde acid substrates. The utility of the method was demonstrated by application to an enantioselective synthesis of (+)-dihydroplakevulin A. This and related processes may be revealing a subtle interplay between [2+2] cycloaddition and nucleophile-catalyzed aldol lactonization (NCAL) reaction manifolds.
authors.affiliation: Department of Chemistry, PO Box 30012, Texas A&M University, College Station, Texas 77842-3012, USA.
authors.forename: Huda
authors.initials: H
authors.lastname: Henry-Riyad
authors.forename: Changsuk
authors.initials: C
authors.lastname: Lee
authors.forename: Vikram C
authors.initials: VC
authors.lastname: Purohit
authors.forename: Daniel
authors.initials: D
authors.lastname: Romo
mesh_terms: D018360:Crystallography, X-Ray; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D007651:Keto Acids / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D008958:Models, Molecular; D013237:Stereoisomerism
chemical_list: D003517:Cyclopentanes; D007651:Keto Acids; D007783:Lactones; C520899:dihydroplakevulin A