Ferrocenes fused

Kurita and co-workers prepared a ferrocene-fused benzophosphole by intramolecular cyclisation of a lithiated precursor (Scheme 2.52). 

In 1996, Fu et al. reported the S3mthesis of the planar chiral heterocycles 64, formally DMAP fused with a ferrocene core [82]. While the original synthesis provided racemic 64a in only 2% overall yield requiring a subsequent resolution by preparative HPLC on a chiral stationary phase, a recently improved synthesis furnished the racemic complexes 64 in 32-40% yield over seven steps. A subsequent resolution with di-p-toluoyltartaric or dibenzoyltartaric acid gave access to the enantiomers with >99% ee (28 14% yield for each isomer in this step) [83]. 

U. H. F. Bunz, G. Roidl, M. Altmann, V. Enkelmann, K. D. Shimizu, Synthesis and Structural Characterization of Novel Organometallic Dehydroannulenes with Fused CpCo-Cyclobutadiene and Ferrocene Units Including a Cydic Fullerenyne Segment , J. Am Chem Soc 1999,121, 10719-10726. 

For general syntheses applied to fused ferrocene, tricarbonyl cyclobuta-dieneiron, and benchrotrene derivatives, see Tables II, IV, V, and VIII.)... 

In 2002, the first synthesis and structure of a stable pentathiepin fused to a single cyclopentadienyl ring of ferrocene was performed by the treatment of the corresponding dithiastannole, as a synthetic equivalent of unstable ferrocene-1,2-dithiol with sulfur dichloride <2002TL5825>. Pentathiepin 129 was synthesized as follows (Scheme 29). 

II. Ferrocenes Containing a Heterocyclic Ring Fused to the Ferrocene. 2... 

Since the discovery of dicyclopentadienyliron (ferrocene) in 1951112 an immense body of literature has appeared concerning the chemistry of ferrocenes and related compounds. Although a large number of reviews3 have appeared, they have given only brief treatment to ferrocenes containing heterocyclic systems. It is the purpose of this review to report on those ferrocenes which contain heterocyclic systems either fused to the ferrocene or as a substituent on the ferrocene. 

For further information on synthesis, properties, and applications of pyrro-lidinofullerenes, the chiral representatives of which were generally prepared and used as racemates, we refer to a recent review by Prato and Maggini.214 Fields in which many fullerene-fused pyrrolidines have been studied are biological and medicinal chemistry351 and, above all, advanced materials science.352,353 In the latter context, dyads and triads used for photoinduced charge separation between a fullerene acceptor moiety and electron donors like porphyrins, tetrathiafulvalenes, ferrocenes, or polyenes, are worth particular mentioning.354-356... 

A series of planar chiral pyridine-fused ferrocene analogs (366) have been prepared and the enantiomers are resolved by chiral High performance (pressure) liquid chromatography (HPLC) see High Performance Liquid... 

Cycloadditions. A chiral 2,2 -bipyridine (69) in which each nucleus is fused to a ferrocene has found use in a CuOTf-catalyzed asymmetric cyclopropanation. "" ... 

Some uses of sugars in novel resolutions of enantiomers have been reported. The ferrocene derivative 225 could be isolated from reaction of a mixture of d,l-and meso-isomers of the corresponding ferrocene dicarbonyl chloride with methyl 4,6-0-benzylidene-a-D-glucopyranoside. This could then be converted by methanolysis into the enantiomerically-pure (R,/ )-ferrocene derivative 226. When the chiral pyridinium salt 227 was photolysed, equimolar amounts of the diastereomers 228 and 229 were obtained. Although no chirality transfer occurred, the two isomers could be separated after acetylation, and some further chemistry was performed on the fused aziridine ring of one of the dia-... 

Dipolar cycloaddition Sidewalls Pyrrolidine rings fused to C-C bonds Addition in situ of azomethine ylides by thermal condensation of aldehydes and a-amino acids Immobilization of ferrocene [59] Electrochemical detection of anions, amino acids, and peptides [60]... 

Optically active dibenzo[c,g]phenanthrene (Af)-(—)-91 bearing two fused cyclopentadienyl rings was synthesized by the photodehydrocyclization method with chirality being controlled during the cyclization process [84]. The optically active helical ferrocene (Af)-(—)-92 was obtained by treatment of (M)-(—)-91 with tcrt-butyllithium followed by FeCl2-2THF (Scheme 19). 

An example of the synthesis of a benzo-fused pyridine (i.e., a quinoline), containing an embedded ferrocene unit shown in structure 187, has been reported by Mamane and Fort [62], Commencing with the bisaldehyde 188 and subjecting it to a Wittig one-carbon homologation at each aldehyde group, it was converted into the bisvinyl complex 189, setting this up for an aUcene RCM reaction to... 

Non-fused iron catalysts have been studied earlier. The famous Uhde catalyst was KAl (Fe(CN)6), which was used, to be applied in industry. It was abandoned because of its poor stability, and up to now there are still reports about its modifications. Intermetallic compound and alloy catalysts, such as LaNij, FeTi, Fe2Ce and FeZr etc., were also expected to be prospective, but until now they have not been put into practice. In 1970s, the well-known electron donor-acceptor (EDA) catalysts, e.g., phthalocyanine iron-alkali metal, molysite — graphite — potassium and ferrocene-activated carbon-potassium catalyst systems, were found to have the ability to synthesize ammonia under mild conditions in the laboratory. Unfortunately, their activities declined rapidly in the experiments of scale-up. The application of EDA catalysts in industry turned to be a visionary. Therefore, replacement of fused iron catalyst is not an easy thing for a very long time. 

The review begins with a selective summary of the history of organome-taUic and reductive rare-earth chemistry as an introduction to bimetallic lanthanide complexes bridged by ligands derived from arenes and to complexes of ferrocene-based diamide ligands, a major subtheme in the chapter. Detailed discussions then follow on complexes derived from fused rings and their reactivity with phosphorus and on complexes derived from biphenyl and stilbene as substrates, with emphasis on ferrocene-based diamide complexes. 

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