Ferrocenyl chloride

Bell and Hall have incorporated an organometallic unit into a crown by using the ferrocenyl unit as part of the ring or as a third strand. The unit is incorporated either as the 1,1 -diformylferrocene or the corresponding acid. In the former case, the bis-imine is prepared and reduced to give the saturated crown (see structure 24). In the latter case, the acid is converted into its corresponding chloride and thence into the diamide by reaction with a diamine. Diborane reduction affords the saturated amino-crown. Structure 24 could be prepared by either of these methods but the dialdehyde approach was reported to be poor compared to the amide approach which afforded the product in ca. 60% yield . 

Thionyl imide, HNSO, is a thermally unstable gas, which polymerizes readily. It can be prepared by the reaction of thionyl chloride with ammonia in the gas phase. Organic derivatives RNSO have higher thermal stability, especially when R = Ar. The typical synthesis involves the reaction of a primary amine or, preferably, a silylated amine with thionyl chloride. A recent example is the preparation of FcNSO (Fc = ferrocenyl) shown in Eq. 9.8. In common with other thionylimines, FcNSO readily undergoes SO2 elimination in the presence of a base, e.g., KO Bu, to give the corresponding sulfur diimide FcNSNFc. 

Another interesting family of phosphine ligands that has been applied to this coupling reaction is the ferrocenyl-phosphines. Some air-stable examples are showed in Figure 3. Compound 20 has been used for the coupling of aryl chlorides in combination with a Pd(0) source,while 21 gave excellent results for the coupling of a variety of aryl... 

The preparation of a bis-O-ferrocenoyl-L-tyrosine peptide 106 has been reported (Scheme 31 ).t69i This compound was rationally designed to be used as a model peptide to study the binding ability of a fullerene-modified silica gel. The attachment of the ferrocenyl units was performed presumably in solution using the free hydroxy tyrosine peptide and ferrocenoyl chloride. 

The reaction of ferrocenylazide and dimethyl e o-cis-3,6-endoxo-A 4-tetrahydrophthalate gives the ferrocenyl compound 68.70 Reaction of cyanoferrocene with trimethylsilyl azide and aluminum chloride gave ferrocenyltetrazole (69) as the sole organometallic product.71 Alkylation of 69 with methyl iodide affords two A-methyl derivatives. The major product is assigned the structure 2-methyl-5-ferrocenyl-tetrazole, while the minor product is assumed to be the 1-methyl isomer. 

In addition, testing scope and limitations of this sequence and the conditions, ferrocenyl substituted isoxazoles 23 were synthesized from ferrocenyl carbonyl chloride (R = ferrocenyl) and/or ethynyl ferrocene (R = ferrocenyl), and were often obtained as red crystals [99]. Unfortunately, standard conditions of the cycloaddition step failed, which had to be conducted at room temperature (Scheme 16). 

One key goal of catalyst development is to move from the more expensive alkyl and aryl iodides and bromides to the cheaper chlorides and the environmentally more desirable tosylates. The latter tend to react less well bnt the nse of basic, bulky ligands like P(tBn)3 and a nnmber of ferrocenyl-substituted phosphines has improved the situation. 

The reactions of Fc-NHj with thionyl chloride or sulfur dichloride lead to ferrocenyl thionylimide, Fc-NSO, and diferrocenyl sulfur diimide, Fc(NSN)Fc, respectively (Scheme 5-10) [68],... 

The synthesis generally involves reaction of either the ferrocenyl chalcogenols and l,l -ferrocenylene dichalcogenols, Fc-EH and fc(EH)2, or (preferably) the corresponding lithium derivatives, Fc-ELi and fc(ELi)2, with halides such as acid chlorides, non-metal chlorides and chloro metal complexes (E = S, Se, Te). 

Thus, all possible acyl derivatives of the three ferrocenyl chalcogenols and the three l,l -ferrocenylene dichalcogenols (E = S, Se, Te) have been obtained [89] by treating the lithio compounds with the carboxylic acid chlorides benzoyl, 2-thenoyl, and ferrocenoyl chloride (Scheme 5-31). 

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