Bis(cyclopentadienyliron)arene complexes: a new route to the synthesis and functionalization of polyaromatic ethers

Abstract

A new development in the chemistry of arenes activated toward SNAr reactions by the cyclopentadienyliron (FeCp+) moiety is presented in this work. A class of diiron complexes of diphenoxybenzenes was prepared in a highly efficient and very mild fashion. Dihydroxy aromatic compounds served as dinucleophiles, allowing for the formation of the diiron complexes. This could be achieved in either a one or two step procedure. A wide variety of dinucleophiles were incorporated into this study, as well as a number of FeCp+ activated arenes. It is shown that these reactions are not inhibited by bulky substituents on either the dinucleophiles or activated arenes. The diiron complexes themselves could also undergo SNAr reactions, provided that the complexed arenes contained a chlorine substituent. This allowed for the functionalization of the complexes with species that could not be introduced directly in their syntheses. The carbon nucleophiles generated from ethyl cyanoacetate or (phenylsulfony1)acetonitrile could be attached to the complexed ethers in this manner. The FeCp+ moieties were removed easily by photolytic demetalation which allowed for the recovery of a wide range of functionalized diphenoxybenzenes. This methodology is advantageous over all those previously reported and should be a practical route to the synthesis of aromatic ethers.

Ironcyclopentadienyl mediated 2-alkyl-2-arylphenylsulphonylacetonitrile synthesis

“…This was demonstrated clearly by the kinetic study carried out by Knipe et al (20,21). As well, the low toxicity and cost of this type of FeCp' complexation makes this route attractive in the synthesis of substituted aroof the cpFe+ complexes of chloroarenes in the synthesis of potentially biologically active molecules (2)(3)(4)(5). We recently reported that chloroarene complexes can undergo nucleophilic aromatic substitution (SNAr) with ethyl cyanoacetate or phenylsulphonylacetonitrile, leading to carbon-carbon bond formation (4,5).…”

“…Since the displacement of the chloro group in the -q6-chlorobenzene--q5-cyclopentadienyliron complex by a number of nucleophiles was first reported (I), numerous publications have appeared describing the use of these complexes in the synthesis of various organic molecules (2)(3)(4)(5)(6)(7)(8)(9)(10). Other metal moieties such as chromium tricarbonyl (Cr(CO),), manganese tricarbonyl (Mn(CO),+), and cyclopentadienylruthenium (CpRu+) have been used in the activation of the haloarene ring towards nucleophilic substitution reactions (11)(12)(13)(14)(15)(16)(17)(18).…”

Nucleophilic addition to di- and poly-iron arene complex cations

“…This versatility is valuable in the investigation of synthetic routes for the functionalization of organic and polymeric compounds. In the past few years, we have been involved in the synthesis and characterization of polyaromatic ethers with or without pendant metallic moieties (44)(45)(46)(47). In this article, we report the addition of cyanide to a number of CpFe+ polyaromatic ether complexes.…”

“…Starting complexes [I, 2, 5 , 7 , 9 , 12,13-281 were prepared by established procedures (45)(46)(47). Sodium borohydride (Alfa), DDQ (Aldrich), and sodium cyanide (Aldrich) are commercially available and were used without further purification.…”

Synthesis of substituted norbornenes and their polymerization to polynorbornenes with flexible aliphatic side-chains

“…The use of cyclopentadienyliron (CpFe + )-mediated nucleophilic aromatic substitution (S N Ar) reactions in the synthesis of both oligomeric and polymeric materials has proven to be very successful [8][9][10][11][12] . The flexible side-chains containing terminal hydroxy groups were synthesized via monosubstitution reactions of aliphatic diols with chlorobenzene complexes (Scheme 1).…”