An improved synthetic method for ifl-giseofulvin (4) and its 2'-S-analogue 8 has been developed. 7-Chloro-4,6-dimethoxy-2-[5-methoxy-l -methylthio-3-oxohexylidene]-3 (2H)-benzofuranone (7), prepared by reaction of the corresponding 3 (2H)-benzofur-anone with l,l-bis(methylthio)-5-methoxy-l-hexen-3-one (6), undergoes stereoselective intramolecular cyclization when treated with activated alumina in refluxing diethyl ether. The product, the 2'-5'-analogue of dl-griseofulvin 8, is converted to dl-griseofulvin (4) in good yield.
ASJC Scopus subject areas
- Organic Chemistry