SYNTHESIS OF HETERODICHALCOGENATED FERROCENES WITH OPEN OR BRIDGING CHAINS BY ADDITION OF FE(C5H4ELI)2.2THF (E = S, SE) TO PROPYNOATES

The addition of lithium salts of 1,1'-ferrocene dithiol and diselenol to propynoates gives exclusively beta-substituted propenoates with predominant (Z,Z)-configuration: Fe(C5H4EC(R) = CHCO2C2H5)2 (E = S, Se, R = H, C6H5). The ester group can be converted sequentially into acid and acid chloride without modification of the configuration. Aluminium trichloride reacts with 1,1'-ferrocenyldi-4-chalcogenabutenoyl chloride (Z,Z) leading to ortho-cyclisation products (E = S) and a rearrangement product (E = Se).