Iron complexes cycloheptadienyl

Cycloheptadienyl-iron complexes. Cyclohcptadienyl-Fe(CO), reacts with nucleophiles to give mixtures of products, usually in low yield. However, complexes 1, in which one CO ligand is replaced by triphenylphosphinc or triphenyl phosphite, react with most nucleophiles at the dienyl terminus and in high yield. Hydride abstraction followed by reaction with a second nucleophile results in a regio- and stereocontrol led substitution at the opposite terminus and again anti to the metal. Decomplexation affords ri.v-5,7-disub-stituted cycloheptadienes. 

Some progress has been made in performing asymmetric variations of this chemistry. Addition of the anion of sulfoximine ester (272) to achiral (cycloheptadienyl)iron cation complex (271, L = P(OPh)3), followed by desullu-rization, affords enantiomerically enriched (273, 50% ee) (Scheme 77). In a similar manner, addition of the enolate derived from a chiral iV-acyloxazolidinone (274) to achiral (cyclohexadienyl)iron cation complex (275) and subsequent auxiliary removal affords (276, 70% ee). 

Initial attempts to prepare 7r-cycloheptatrienyl-iron tricarbonyl complexes were not successful—the products often being 7r-cycloheptadienyl-iron tricarbonyl derivatives (60). In 1964 Mahler, Jones, and Pettit (162) reported the synthesis of a complex [(C7H7)Fe(CO)3] BF4 by the following route ... 

Unstable (C6H6)aRu has been prepared from Ru vapour and benzene n.m.r. spectra confirm the l-4-i l-6-j co-ordination of the benzene ligands. Reaction of [RuCl2(arene)]a complexes with cod, chd, or ethylene in the presence of base (NaaCOs) or zinc dust yields (arene) RuLa complexes (La=cod or chd L=Ca-Hi) under similar conditions, chpt yields the protonation product [(arene)Ru-(cycloheptadienyl)]+. Some of the analogous iron complexes have also been prepared, and the reactivity of the Ru complexes towards electrophiles resembles closely that of the isoelectronic CpRh(diene) series. 

Iron carbonyl complexes containing 77 -alkyl-77 -allyl coordinated hydrocarbon ligands are obtained in several ways. Nucleophilic addition to cationic iron complexes containing 77 -pentadienyl ligands yields (pentenediyl)iron complexes. Oxidatively-induced reductive elimination of these complexes can be utilized as a means to generate 1,2,3-trisubstituted cyclopropanes.The reaction of cationic cycloheptadienyl complexes (Scheme 22) with appropriate nucleophiles also yields the alkyl-allyliron carbonyl complexes. Fe(CO)s also reacts with a- or /3-pincnc in refluxing dioxane (Scheme 22) to produce an alkyl-allyliron complex. Recently, 1,2- and 1,4-disubstituted [(pentadienyl)Fe(CO)3] cations were shown to react with carbon nucleophiles, such as sodium dimethylmalonate, to yield 77 77 -allyl complexes as products. 

The analogous cycloheptadienyl complex (5 equation 1) was similarly prepared by Dauben and Ber-telli,4 but the acyclic pentadienyl systems were a little more difficult to obtain. The triphenylmethyl cation does not remove hydride from tricarbonyl(frans-pentadiene)iron (6 equation 2). The corresponding c/s-pentadiene complex (7 equation 3) cannot be prepared directly from the diene and an iron carbonyl,... 

Beck and co-workers (84,8.5) utilized the anionic carbonylmetallates [M(C0)5] (M = Mn, Re) and [WCp(CO),] in nucleophilic addition reactions with cationic hexadienyl, cyclohexadienyl, cycloheptadienyl, and cyclooctadienyl complexes of iron and ruthenium to give heterobimetal lie complexes with rj iV-hydrocarbon bridges. The reaction of [Fe(i7 -... 

The reaction of the iron-carbene complex [[Bu C CC(OEt)=)Fe(CO)4] with 1,3-cyclohexadiene afforded223 (32), which was characterised by X-ray diffraction. The addition of the anionic derivatives of i-(diphenylmethane)-il-fluorene- and ii-(9,10-dihydroanthracene)-bis tricarbonylchromium to the hydrocarbon moiety (alkene, benzene, cyclohexadienyl, cycloheptadienyl and cycloheptatrienyl) in various cationic compounds of manganese, rhenium, iron, chromium, molybdenum, tungsten and cobalt was reported224 to provide a new route to hydrocarbon-bridged heteronuclear species such as (33). 

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