title: A Serendipitous Synthesis of Bis-Heterocyclic Spiro 3(2H)-Furanones.
abstract: (Z) Enol triflates 6, 11b-d, (E) enol triflate 11e, and phenol triflate 11a, derived from β-keto esters or 2-carboalkoxy phenols, respectively, react with N-Boc 2-lithiopyrrolidine (5a), N-Boc N-methylaminomethyllithium (5b), or 2-lithio-1,3-dithiane (14) to afford 3(2H)-furanones in modest to good yields (38-81%). Product and carbanion reagent studies suggest that the 3(2H)-furanone is formed in a cascade of reactions involving nucleophilic acyl substitution, enolate formation, trifluoromethyl transfer, iminium or sulfenium ion formation, and subsequent ring closure to form the 3(2H)-furanone. The use of 2-lithio-1,3-dithiane affords a cyclic α-keto-S,S,O-orthoester in which the functionality can be selectively manipulated for synthetic applications.
authors.affiliation: Hunter Laboratory, Department of Chemistry, Clemson University , Clemson, South Carolina 29634-0973, United States.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Picado
authors.affiliation: Hunter Laboratory, Department of Chemistry, Clemson University , Clemson, South Carolina 29634-0973, United States.
authors.forename: ShengJian
authors.initials: S
authors.lastname: Li
authors.affiliation: Hunter Laboratory, Department of Chemistry, Clemson University , Clemson, South Carolina 29634-0973, United States.
authors.forename: R Karl
authors.initials: RK
authors.lastname: Dieter