title: Total syntheses of the dihydrofuranonecarboxylate natural products gregatin B and E: gram-scale synthesis of (+)-gregatin B and unambiguous assignment of the stereostructure of (+)-gregatin E.
abstract: We synthesized the dextrorotatory enantiomers of gregatin B (1.3 g scale) and E, establishing their diene side chains in the last step by Heck coupling with variable iodoolefins. Their counterpart was synthesized in 30% overall yield and with high enantiopurity (97% ee) from benzyl tiglate, beginning with an asymmetric dihydroxylation. The stereostructure of gregatin E followed from HPLC comparisons between the four synthetic stereoisomers of this compound and natural gregatin E, which we isolated from Cadophora gregata.
authors.affiliation: Institut für Organische Chemie, Albert-Ludwigs-Universität , Albertstraße 21, 79104 Freiburg im Breisgau, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Weber
authors.forename: Reinhard
authors.initials: R
authors.lastname: Brückner
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D001688:Biological Products; D005663:Furans; C559559:gregatin B; C587470:gregatin E