title: Studies on the total synthesis of lactonamycin: construction of model ABCD ring systems.
abstract: Model studies on the synthesis of the tetracyclic ABCD ring system of lactonamycin (1) are described. The key step involved the double Michael addition reaction of alcohol 8 to propynoate esters to produce the BCD units 13 and 14 of the target 1. Alternatively, double Michael addition of alcohol 8 to di-tert-butyl acetylenedcarboxylate gave the corresponding BCD ring systems 36 and 37. Acid-mediated hydrolysis of the dihydroquinone monoketal units of 13 and 14 and 36 and 37 in the presence of air gave the corresponding quinones 7 and 39. These were converted into the tetracyclic ABCD units 6, 26a, 40, and 42 of lactonamycin (1) by either dihydroxylation or epoxidation and acid-catalyzed lactonization.
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, England.
authors.forename: David A
authors.initials: DA
authors.lastname: Henderson
authors.forename: Philip N
authors.initials: PN
authors.lastname: Collier
authors.forename: Gregoire
authors.initials: G
authors.lastname: Pavé
authors.forename: Paula
authors.initials: P
authors.lastname: Rzepa
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Burrows
authors.forename: Anthony G M
authors.initials: AG
authors.lastname: Barrett
mesh_terms: D003500:Cyclization; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D009285:Naphthoquinones / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D007211:Indoles; D009285:Naphthoquinones; C102442:lactonamycin