title: Synthesis of the parent and substituted tetracyclic ABCD ring cores of camptothecins via 1-(3-aryl-2-propynyl)- 1,6-dihydro-6-oxo-2-pyridinecarbonitriles.
abstract: A new synthetic pathway to the parent and substituted ABCD ring cores of the camptothecin family of alkaloids was developed. The N-alkylation of 1,6-dihydro-6-oxo-2-pyridinecarbonitrile (2) with 3-bromo-1-phenylpropyne provided 3a using Curran's protocol. Treatment of 3a with a catalytic amount of DBU (5 mol %) at 110 degrees C for 12 h produced indolizino[1,2-b]quinolin-9(11H)-one (6a), the parent ABCD ring core of camptothecin, in essentially quantitative yield.
authors.affiliation: C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA.
authors.forename: Weixiang
authors.initials: W
authors.lastname: Dai
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Petersen
authors.forename: Kung K
authors.initials: KK
authors.lastname: Wang
mesh_terms: D002166:Camptothecin / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D009570:Nitriles / Q000737:chemistry*
chemical_list: D009570:Nitriles; D002166:Camptothecin