128456-69-9Relevant academic research and scientific papers
Umpolung of Tropone: The Reaction of 2-Halogenocycloheptadienone Enolates with Tropylium Cations and Several Other Cationic Electrophiles. Preparation of Novel 2-Substituted and 2,7-Disubstituted Tropones
Miyano, Hiroyuki,Nitta, Makoto
, p. 839 - 845 (2007/10/02)
The reactions of 2-halogenotropones (3a-c) with hydride reagents giving 2-halogenocycloheptadienone enolates (4a-c) have been studied to provide a reverse polarity (umpolung) of tropone.The structures of 2-chlorocycloheptadienone enolate (4a) and 2-chloro-7-deuteriocycloheptadienone enolate (4D) were confirmed by 1H NMR spectral studies.The enolates were easily reacted with tropylium and substituted tropylium cations to give 2-(2,4,6-cycloheptatrienyl)tropone (8) and its derivatives (13b-d) and (14b-d) in good yields.The other cationic electrophiles, such as benzo- and dibenzotropylium cations, di- and triphenylcyclopropenylium cations as well as tricarbonyl(cyclopentadienylium)iron and tricarbonyl(cyclohexadienylium)iron, were also reacted with the enolate to give the corresponding 2-substituted tropones (21-27) in good to modest yields.In a similar fashion, 2-halogeno-7-substituted cycloheptadienone enolates (28a-e) were generated through the reaction of 2-chlorotropone (3a) with Grignard and organolithium reagents as well as the reaction of 2-bromo-7-methoxytropone (3d) and 2,7-dibromotropone (3e) with hydride reagent.They reacted also with tropylium cation to give 2,7-disubstituted tropones (29a-e).
