Studies on selective nucleophilic substitution reactions of [(cyclopentadienyl)(1,3-dichlorobenzene)M]+ PF6- complexes (M = iron, ruthenium)

Preparation of Functionalized p-Phenylenediamine Derivatives Using Arene−Iron Chemistry

“…Synthesis of Donor − Acceptor Systems. The possibility of obtaining unsymmetrically substituted arenes by sequential, chemoselective S N Ar reactions on dichlorobenzene FeCp cations is well precedented. ,, We have applied this methodology to the preparation of the unsymmetrical phenylenediamine complexes 23 and 24 . Unfortunately, we were not able to obtain acceptable selectivity with piperazine as the first nucleophile.…”

“…Transition-metal activated nucleophilic aromatic substitution is beginning to play a role in various polymer and materials applications. − While triaryl-diether and polyphenylene oxide derivatives that are accessible from these complexes have been thoroughly investigated, − other derivatives, such as N-substituted phenylenediamines, have seen far less attention. While several well known methods for the construction of the arene−nitrogen bond may be found, these reactions either proceed via a benzyne intermediate, and suffer the attendant regiocontrol problems, or they require high temperatures (Ullmann conditions) or the presence of specific functionality on the ring (traditional S N Ar reactions).…”

Strained cyclophane natural products: Macrocyclization at its limits

“…[208][209][210][211][212][213] The difficulty in accessing fully synthetic 14-membered cycloisodityrosine compounds has hampered in-depth studies on their medicinal potential and their mode of action for many years. 210,[214][215][216][217][218][219][220][221][222][223][224][225] The severe ring strain in these derivates led to many failures in their attempted preparation, especially in the macrocyclization step. 161,210 The most obvious reaction for ring closure of cyclopeptides would of course be a macrolactamization, 226,227 which has, however, never been achieved for cycloisodityrosine-containing compounds.…”

SNAr catalysis enhanced by an aromatic donor–acceptor interaction; facile access to chlorinated polyfluoroarenes

“…9-11 Transition metal activation of haloarene C–X bonds toward nucleophilic substitution is achieved via complexation of the π-cloud of the arene to a metal center, which polarizes the substrate. 12, 13 In contrast, the quadrupole of perfluoroarenes is inverted, 14 and thus, this activation is not feasible. 6, 15 While S N Ar addition of a variety of traditional nucleophiles are prevalent in literature 8, 16 the use of chloride as a nucleophile to displace a fluoride is rather limited and to the best of our knowledge, catalytic reactions to selectively substitute C–F with C–Cl are not known.…”