Ferrocene acylation alumina

Table 4.15 Ferrocene acylation with carboxylic acid-TFAA mixtures promoted by alumina...

NOTE. This procedure prevents overloading of the chromatographic column during the separation of the reaction products. If the yield of crude reaction products exceeds 75 mg (the usual case), introduce one-half of the alumina-product mixture to the column. If the crude products, however, are obtained in quantities of less than 75 mg, add the entire alumina-product mixture to the top of the column. If only one-half of the alumina-crude ferrocene acylation product mixture is placed on the column, it is important to reweigh the tared vial to establish a reasonably accurate estimate of the overall yields obtained in the reaction. 

Friedel-Crafts acylation of ferrocene gave the ketone (193) which was oxidized rapidly on alumina columns to the diketone.63 The action of phosphorus oxychloride-dimethylformamide on 193 gave 194 and then 195, which could then be converted into the ferrocenyl-acetylene (196).63... 

An efficient and ecofriendly procedure for the small-scale acylation of ferrocene with carboxylic acids is based on the in situ production of the mixed carboxylic-triflic anhydride (Table 4.15 see also Chapter 3). The reaction is simply performed by adsorbing ferrocene on the surface of activated alumina (preheated at 150°C for 3 h) and adding a mixture of carboxylic acid and trifluoroacetic anhydride (TFAA) at room temperature for a selected time. Products 40 are recovered in 55%-98% yield simply by elution with diethyl ether. 

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