Synthesis of putative intermediates in the biosynthesis of the kinamycin antibiotics: total synthesis of phenanthroviridin aglycon and related compounds
作者:Makarand P. Gore、Steven J. Gould、Dwight D. Weller
DOI:10.1021/jo00036a005
日期:1992.5
Phenanthroviridin aglycon, 14, recently isolated from Streptomyces viridiochromogenes DSM 3972, and the corresponding pyridone 10 have been synthesized from the common intermediate (bromoaryl)naphthamide 42. This was prepared by condensation of a (trimethylsilyl)ethyl (bromoaryl)cinnamate 36 and a methoxy-substituted cyanophthalide anion 15, providing the ABD rings of the target benzo[b]phenanthridine skeleton. The aglycon 14 was obtained by a sequence of metal-halogen exchange and formylation, Hofmann rearrangement, cyclization, and deprotection. The pyridone was obtained by Hofmann rearrangement, metal-halogen exchange, cyclization, and deprotection. In addition, a route to cinnamate 36 via coumarin 49 was developed which would allow selective protection of the 1-hydroxyl group for synthesis of glycosidic analogues of phenanthroviridin, 13. The methodology developed is useful for preparation of 10, 14, and analogues specifically labeled at C-5 for study of biosynthesis of the kinamycin antibiotics.