Synthesis of 1,2-diferrocenyl-3-(diacylmethylidene)cyclopropenes and 1,1-diacyl-2,3-diferrocenyl-4-methylsulfanylbuta-1,3-dienes, their structures and electrochemical properties

A Novel Synthesis of Ferrocenylpyridazines

“…Opening of the three-membered ring [20] of bicyclic intermediates 5a-f involves the C-3 bridgehead carbon atom bearing the ferrocenyl substituent and follows the conventional pathway to afford ferrocenyl(vinyl)carbenes. [21][22][23][24] Aromatization of vinylcarbenes with migration of the hydrogen atoms to the carbene site ultimately results in pyridazines.…”

“…Hydrazones 4d and 4e [21] have previously been identified by us as the primary reaction products of 2d and 2e with hydrazine at 15-20°C, and they were isolated from the reaction mixtures and characterized by using physicochemical methods. To confirm the postulated mechanism of pyridazine formation, we have examined the behavior of hydrazones 4d and 4e on prolonged storage of their solutions in benzene and acetonitrile at ambient temperature and on brief heating at reflux.…”

“…Hydrazones 4d and 4e were obtained by treating ethanolic 2d and 2e with hydrazine monohydrate (3 h at 20°C; yields 60-62 %). [21] Reaction of Dialkylamino(diferrocenyl)cyclopropenylium Tetrafluoroborates with 1,3-Cyclohexanedione 1f: β-Diketone 1f (6 mmol) and Et 3 N (10 mL) were added with stirring to a mixture of diferrocenyl(morpholino)-or (piperidino)cyclopropenylium tetrafluoroborates (3 mmol) in dry benzene (50 mL). After stirring for 6 h at 80°C, the volatiles were removed in vacuo; chromatography of the residue on Al 2 O 3 (hexane/dichloromethane, 10:1) gave 2f.…”

Intramolecular Transformations of 3-Cyanoamino- and 3-Cyanoimino-1,2-diferrocenylcyclopropenes

“…The presence of ferrocenyl substituents in the three-membered ring greatly facilitates these ring opening reactions [ 9 , 10 , 11 , 12 , 13 ]. This allows the use of ferrocenylcyclopropanes/cyclo-propenes prepared by directed synthesis for their subsequent transformation into long-chain conjugated systems [ 6 , 8 ] and carbo- and heterocycles [ 14 , 15 , 16 , 17 ] incorporating iron-containing fragments. The effect of the nature of other functional groups and hetero-substituents on the ease of the three-membered ring opening of ferrocenylcyclopropenes has been but scantily explored.…”

“…The effect of the nature of other functional groups and hetero-substituents on the ease of the three-membered ring opening of ferrocenylcyclopropenes has been but scantily explored. In particular, it has been established that the small ring opening occurs very readily for 2,3-diferrocenyl-1-methylthiocyclo-propenes 1a-d [ 15 , 16 , 17 , 18 , 19 ]. These are formed in the reaction of diferrocenyl(methylthio)cyclopropenylium iodide ( 2 ) with active methylene reagents (diethyl malonate, malononitrile, nitroalkanes) and are further converted via 2,3-diferrocenyl-1-methylthiovinylcarbenes 3a-d into diene systems 4a-d with ferrocenyl substituents and terminal functionalities as a result of intramolecular migration of a functional group ( Scheme 1 ).…”