title: Selective Intermolecular Photo-[4 + 4]-cycloaddition with 2-Pyridone Mixtures. 3. Synthetic Transformations of the Trans Cross-Product (1alpha,2beta,5beta,6alpha)-3-Butyl-9- methoxy-3,7-diazatricyclo[4.2.2.2(2,5)]dodeca-9,11-diene-4,8-dione.
abstract: Transformations of the tricyclic product 3 derived from [4 + 4] photocycloaddition of N-butyl-2-pyridone with 4-methoxy-2-pyridone has demonstrated, for the first time, facile opening of the secondary lactam after activation of the amide nitrogen with a tert-butyl carboxylate (Boc) group. Methanolysis and lithium borohydride reduction both result in opening of the amide group under very mild conditions to give 21 and 24, respectively. Concomitant reduction of a ketone derived from hydrolysis of the enol ether sets an additional stereogenic center in 24 with complete stereogenic control. These reactions illustrate the synthetic potential of the 2-pyridone photocycloaddition products, generating a cyclooctene as a single isomer, with functionality at seven carbons and five stereogenic centers.
authors.affiliation: Department of Chemistry, State University of New York, Stony Brook, New York 11794-3400.
authors.forename: Scott McN.
authors.initials: SM
authors.lastname: Sieburth
authors.forename: David
authors.initials: D
authors.lastname: Rucando
authors.forename: Chao-Hsiung
authors.initials: CH
authors.lastname: Lin