3,5-bis(ferrocenylmethylene)-1-methyl-4-methylenepiperidine. Synthesis andsome chemical properties

3,5-Bis(ferrocenylmethylene)-1-methyl-4-methylenepiperdine, a diferrocenylt riene with a fixed s-cisoid conformation of the exocyclic double bonds, was synthesized. On heating, this compound cyclodimerizes according to the [42]-cycloaddition scheme; it forms Diels-Alder adducts with azodicarboxylic and maleic acid N-phenylimides. The compound easily cyclodimerizes in the p resence of acids by a proton cyclodimerization mechanism to give a spiro cy clodimer. The triene also adds a 3,5-bis(ferrocenylmethylene)-1,4-dimethyl- 1-azonia-4-cyclohexyl salt to the terminal methylene group yielding linear and cyclic addition products.