Cyclopentadienyliron dicarbonyl anion

The cyclopentadienyliron dicarbonyl anion was reacted with an optically active chlorosilane giving rise to an optically active iron complex58 (equation 8) which was isolated in 98% optical purity. On the basis of the known stereochemistry of nucleophilic displacement of chlorine nucleofuge, the reaction was assumed to occur with inversion of configuration at silicon. 

Phase-transfer catalysis has also been found to be superior to NaK or Na/Hg for generation of the cyclopentadienyliron dicarbonyl anion from bis(dicar-bonylcyclopentadienyliron), [C5H5Fe(CO)a]a.i Cetyltrimethylammonium bromide, Ci6H33N(CH3)a Br , and 18-crown-6 are about equally satisfactory as catalysts. The anion was used in a synthesis of fulvenes from thiobenzophenones (equation II). 

Reactions of thioketones with nucleophilic reagents have been studied to some extent. Thiobenzophenone (20) and its 4,4 -substituted derivatives react with cyclopentadienyliron dicarbonyl anion and cyclopentadienyl-molybdenum or -tungsten tricarbonyl anion at room temperature to give fulvenes. Phase-transfer catalysis conditions improve the yields. An electron-transfer mechanism has been proposed for this desulphurization and coupling reaction. An electron-transfer mechanism has also been proposed for the reduction of thiopivalophenone (54) by 1-benzyl-1,4-dihydronicotinamide in acetonitrile. 2,3-Diphenylcyclopropene-thione (55) reacts with 7V-methylarylamines to give the bicyclic thioamides (56). The formation of a thioketen as an intermediate has been suggested. A similar reaction scheme has also been proposed for the reaction of (55) with 3,4-dihydroisoquinoline. ... 

Reaction of the cyclopentadienyliron dicarbonyl anion, readily prepared from commercially available cyclopentadienyliron dicarbonyl dimer and sodium amalgam, with epoxides gives olefin complexes (XXXI) in good yields. The olefin ligand can be liberated from the complex using iodide ion (Giering et aU 1972). The reaction occurs with net retention of configuration and was proposed to occur via intermediates XXIX and XXX. 

Cycloaddition reactions of 18-electron transition metal ti -allyl complexes with unsaturated electrophiles to form five-membered rings have been extensively investigated. These transformations constituted a family of metal-assisted cycloaddition reactions in which the metal functions as an electron-donor center. These are typically two-step processes that involve the initial formation of a dipolar metal r) -alkene intermediate (2) and subsequent internal cyclization (equation 2). The most extensively investigated application of this methodology has been with dicarbonyl-ii -cyclopentadienyliron (Fp) complexes from the laboratory of Rosenblum. These (ri -allyl)Fp complexes are available either by metallation of allyl halides or tosylates with a Fp anion, or by deprotonation of (alkene)Fp cations. ... 

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