Synthesis of the isoquinocycline-pyrrolopyrrole substructure.
The synthesis of the pyrrolopyrrole substructure of the isoquinocyclines is reported. The pentacyclic (CDEFG) substructure of isoquinocycline A and B, which contains an unusual 2,4,5,6-tetrahydropyrrolo[2,3-b]pyrrole (FG) connected via an N,O-spiro acetal to the anthraquinoid core of the isoquinocycline aglycon has been synthesized. Key steps were a nickel(0)-mediated hydrocyanation of an alkynone, the conversion of an O,O-acetal into an N,O-acetal, and an intramolecular amidine alkylation.
Cordes
Jens
J
Fachbereich Chemie, Philipps-University Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
Harms
Klaus
K
Koert
Ulrich
U
D000478:Alkylation; D000617:Aminoglycosides / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D000617:Aminoglycosides; D006027:Glycosides; D011758:Pyrroles; C553699:isoquinocycline A; C455260:kosinostatin