title: The imidato-alkenyllithium route for the synthesis of the isoquinocycline-pyrrolopyrrole substructure.
abstract: A convergent and effective synthesis of the pyrrolopyrrole substructure (CDEFG) of the isoquinocyclines is reported. A key step is a tin-lithium exchange of an imidato-alkenyltin compound (a ring G equivalent) and the subsequent acylation with a lactone. The resulting acetal is used successfully for the ring F closure to the pyrrolopyrrole. The sole formation of the isoquinocycline N,O-acetal epimer is in accordance with the proposed mechanism for the isomerization of quinocyclines to isoquinocyclines.
authors.affiliation: Fachbereich Chemie, Philipps-University Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: M André
authors.initials: MA
authors.lastname: Breuning
authors.forename: Klaus
authors.initials: K
authors.lastname: Harms
authors.forename: Ulrich
authors.initials: U
authors.lastname: Koert
mesh_terms: D000617:Aminoglycosides; D003500:Cyclization; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D007783:Lactones / Q000737:chemistry; D008094:Lithium / Q000737:chemistry; D015394:Molecular Structure; D011758:Pyrroles / Q000737:chemistry*; D013237:Stereoisomerism; D013304:Streptomyces aureofaciens / Q000737:chemistry; D014001:Tin / Q000737:chemistry
chemical_list: D000617:Aminoglycosides; D006027:Glycosides; D007783:Lactones; D011758:Pyrroles; C553699:isoquinocycline A; C455260:kosinostatin; D014001:Tin; D008094:Lithium