title: Free radical 5-exo-dig cyclization as the key step in the synthesis of bis-butyrolactone natural products: experimental and theoretical studies.
abstract: Radical cyclization reactions were performed by 5-exo-dig mode to yield cis-fused bicyclic systems, leading to the synthesis of bis-butyrolactone class of natural products. The study was aimed at understanding the impact of alkyl side chains of furanoside ring systems in L-ara configuration on the radical cyclization. It was amply demonstrated by experimental studies that the increase in the length of the alkyl side chain has an effect on the cyclization: while efficient cyclization reactions could be realized with methyl and ethyl side chains, the yields were significantly reduced in the case of n-pentyl side chain. Theoretical studies using DFT and (RO)MP2 methods were carried out to analyze the influence of the substitution pattern on the cyclization barriers.
authors.affiliation: Organic Chemistry Division III, Indian Institute of Chemical Technology (CSIR), Hyderabad, India. esmvee@iict.res.in
authors.forename: Gangavaram V M
authors.initials: GV
authors.lastname: Sharma
authors.forename: Devoju Harinada
authors.initials: DH
authors.lastname: Chary
authors.forename: Nagula
authors.initials: N
authors.lastname: Chandramouli
authors.forename: Florian
authors.initials: F
authors.lastname: Achrainer
authors.forename: Sateesh
authors.initials: S
authors.lastname: Patrudu
authors.forename: Hendrik
authors.initials: H
authors.lastname: Zipse
mesh_terms: D001685:Biological Factors / Q000138:chemical synthesis* / Q000737:chemistry; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000138:chemical synthesis* / Q000737:chemistry; D002090:Butyrophenones / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D001685:Biological Factors; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002090:Butyrophenones; D005609:Free Radicals