Facile syntheses of 2,4,6-cycloheptatrienyl ketones

Abstract

The synthesis of the 2,4,6-cycloheptatrienyl ketones 1a-1e by two alternative routes is reported: Route 1): The adducts 3a-c from the phenyl(trimethylsiloxy)-acetonitriles 2a-c, known as "umpolung" reagents, and tropylium tetrafluoroborate are cleaved by triethylammonium fluoride to form the aromatic cycloheptatrienyl ketones 1a-1c. Route 2): the phenyl, methyl, and cyclopropyl ketone (1a, 1d, 1e) are prepared by treatment of the acid chloride 7 with the corresponding organomanganese iodides RMnI (8a, 8d, 8e). The Fe-catalyzed coupling reaction of the acid chloride 7 with a Grignard reagent was also used for the preparation of ketone 1b. © 1985.