125841-85-2Relevant academic research and scientific papers
On the reactivity of tricarbonyl(1-4-η-cyclohepta-1,3,5-triene)iron derivatives: C-C bond formation of tricarbonyl(cycloheptatrienide)irons with 2-chlorotropone
Nitta, Makoto,Nishimura, Masaki,Miyano, Hiroyuki
, p. 1019 - 1024 (1989)
Tricarbonyl(1-4-η-cyclohepta-1,3,5-triene)iron derivatives [(RC 7H7)Fe(CO)3] (R = H, OMe, CN, and Ph) (4a-d) have been prepared and a study made of the nucleophilic attack of 2-chlorotropone by their corresponding anions. The tricarbonyl(cycloheptatrienide)iron and tricarbonyl(methoxycycloheptatrienide) iron undergo the reaction to give tricarbonyl[1-4-η-7-(2-oxocyclohepta-1,3, 5-trienyl)cyclohepta-1,3,5-triene]iron (7a) and tricarbonyl[1-4-η-6-methoxy- 7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (7b), respectively. In contrast, tricarbonyl(cyanocycloheptatrienide)iron reacted with 2-chlorotropone to afford tricarbonyl[1-4-η-6-cyano-7-(2-oxocyclohepta-1,3, 5-trienyl)cyclohepta-1,3,5-triene]iron (7c) and tricarbonyl[1-4-η-5-cyano-7- (2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (9c) in a ratio of (7c)/(9c) = 1:5.6. Similarly, tricarbonyl(phenylcycloheptatrienide)iron with 2-chlorotropone also affords two products, tricarbonyl[1-4-η-6-phenyl-7-(2- oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (7d) and tricarbonyl[1-4-η-2-phenyl-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3, 5-triene]iron (10d), in a ratio of (7d)/(10d) = 3:1. The selective formation of (7b) and the product ratios of (7c):(9c) and (7d):(10d) are discussed on the basis of the electronic and steric factors of the substituent in the formally unco-ordinated allyl anion on the cycloheptatrienide ring. The stereochemistry of the tropone nucleus at C-7 is deduced to be exo to the [Fe(CO)3] entity on the basis of 1H n.m.r. spectral results. The products (7a, b, d) are easily decomplexed by trimethylamine oxide to give 7-(2-oxocyclohepta-1,3,5-trienyl)- and 1-substituted 7-(2-oxocyclohepta-1,3,5- trienyl)cyclohepta-1,3,5-triene derivatives in good yields.
