title: Reactivity umpolung in intramolecular ring closure of 3,4-disubstituted butenolides: diastereoselective total synthesis of paeonilide.
abstract: Remarkable reactivity reversal stratagem in 3,4-disubstituted butenolides under acidic conditions is described. Design of a suitably substituted multifunctional butenolide followed by an acid-catalyzed chemo- and diastereoselective intramolecular ring closure via the reactivity umpolung has been demonstrated to accomplish a concise total synthesis of paeonilide. Overall, the present protocol involves one-pot reduction of an α,β-unsaturated carbon-carbon double bond and intramolecular nucleophilic insertion of oxygen function at the electron-rich γ-position of butenolide. The involved mechanistic aspects have also been discussed.
authors.affiliation: Division of Organic Chemistry, National Chemical Laboratory (CSIR) , Pune 411 008, India.
authors.forename: Prashant S
authors.initials: PS
authors.lastname: Deore
authors.forename: Narshinha P
authors.initials: NP
authors.lastname: Argade
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry; D003500:Cyclization; D015394:Molecular Structure; D013237:Stereoisomerism; D013729:Terpenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D013729:Terpenes; C416702:paeonilide; C004511:butenolide; D015107:4-Butyrolactone