Alkynylferrocenes react with tetracyanoethylene (TCNE) to form 2-ferrocenyl-1,1,4,4-tetracyanobutadienes. These reactions occur under mild reaction conditions in almost quantitative yields if the triple bond is electron-rich. Systems with more than one triple bond, namely, 1,1Ј-dialkynylferrocenes or diynylferrocenes, react once at the more electron-rich triple bond, and the second reaction cannot be achieved, even under more-forcing reaction conditions. For a diyne with the [a]

Oligophenylene‐ethynylenes are a popular class of molecular wires for molecular electronics. Replacement of some, not all, of the 1,4‐phenylene units by 1,1′‐ferrocenylene moieties generates less rigid entities with a limited conformational flexibility. Within this concept, the syntheses of some 1,1′‐disubstituted ferrocenes that bear arylethynyl or 4‐(arylethynyl)phenyl substituents is presented. In contrast to related compounds with sulfur end groups that were prepared previously, the versions presented here have nitrile end groups, which, according to reported precedence, may serve as points of attachment to gold surfaces. A crystal structure analysis of an unusual diferrocenylethyne derivative is included. In addition, one representative with a push‐pull disubstitution that has a nitro and a dimethylamino end group is presented. Many of the prepared compounds have been characterized by cyclic voltammetry.

In the construction of ferrocene‐based molecular wires, alkyne metathesis was investigated as an alternative to palladium‐catalyzed coupling reactions for the synthesis of alkynyl ferrocenes. With a Mortreux catalyst system [Mo(CO)6, 4‐chloro‐ or 2‐fluorophenol], (1‐propynyl)ferrocenes gave the expected homo metathesis products in moderate yields. Because the Mortreux catalyst system is not compatible with 1,1′‐dialkynylferrocenes, a nitridomolybdenum catalyst introduced by Fürstner was tested in bidirectional homo and cross‐alkyne metathesis reactions. Although the homo alkyne metathesis products were obtained in poor yields, the cross‐alkyne metathesis reactions afforded the expected products in good overall yields.

Some new aryloxy [4]ferrocenophanedienes are described, which have been obtained by reaction of 1,1′-di(1-propynyl)ferrocene and respective phenols. These include one case of a twofold reaction of this type. The possibility of using the products as substrates in Diels-Alder cycloadditions was evaluated with the result that only the most reactive dienophile, 4-phenyl-1,2,4-triazoline-3,5-dione, underwent this reaction. The cycloadduct has an unprecedented structure in that the ferrocene moiety 1,4-diaxially caps a boat conformer of a cyclohexane moiety.

Reactions of Alkynyl-and 1,1'-Dialkynylferrocenes with Tetracyanoethylene -Unanticipated Addition at the Less Electron-Rich of Two Triple Bonds. -The reaction of ferrocenyl substituted internal alkynes with tetracyanoethylene yields adducts of type (III) in generally good to excellent yields. Unsymmetrical diynylferrocenes (Id) or 1,1'-dialkynylferrocenes react once at the less electron-rich triple bond. -(KRAUSSE, N.; KIELMANN, M.; MA, J.; BUTENSCHOEN*, H.; Eur. J. Org. Chem. 2015, 12, 2622-2631, http://dx.doi.org/10.1002/ejoc.201500105 ; Inst. Org. Chem., Univ. Hannover, D-30167 Hannover, Germany; Eng.) -Mais 33-232