The Synthesis of Bridged Ferrocene Derivatives with Functional Groups on the β-Carbon of the Bridge

Abstract

For future mechanistic studies it was desirable to have bridged ferrocene derivatives with functional groups on the β-carbon of the bridge. To this end, the dimethyl ester of ferrocene-1,1'-diacetic acid, was treated with sodium triphenylmethyl in anhydrous ether. The red color of the triphenylmethyl anion soon disappeared and after work-up and chromatography there was obtained in 85% yield 1,1’-(α-carbomethoxy, β-ketotrimethylene)ferrocene which was directly hydrolyzed and decarboxylated in glacial acetic acid with hydrochloric acid to 1,1'-(α-ketotrimethylene)ferrocene (I). Reduction of the ketone with sodium borohydride led to 1,1'- β-hydroxy-trimethylene)ferrocene. The structure of the ketone was proved by desulfurization of its dimethylthioketal derivative with Raney nickel which produced the known 1,1'-trimethyleneferrocene.