Bridged ferrocenes—VI

[1.1]Ferrocenophane‐1,12‐dione as a Precursor of 1,12‐Di(cyclopenta‐2,4‐dienylidene)‐[1.1]ferrocenophane, a Doubly Bridged Difulvene

“…[35,36] However, in our hands the reaction never went to completion, often the starting material was consumed, presumably by adsorption on the metal oxide without adequate product formation. As MnO 2 oxidations are known to frequently give varying results depending on the specific MnO 2 used, we tried to perform the oxidation of 3 with dichlorodicyanoquinone (DDQ) in dichloromethane at 25 8C, and it was found that this reagent effected the double oxidation of 3 in a good and reproducible yield of 76%.…”

“…Compounds obtained from 2 by Barr et al include 3, which was obtained by reduction with LiAlH 4 /AlCl 3 in 87% yield, the 1,12-dimethyl-1,12-diol 4 obtained by reaction with MeMgI, which was reported to be unstable and was reduced with LiAlH 4 /AlCl 3 to the 1,12-dimethyl derivative 5. [36] In order to test the implementation of unsaturated substituents, the diaddition of phenyllithium followed by reduction with LiAlH 4 /AlCl 3 was tried and led to 6 in 39% yield. The compound had earlier been prepared by a different route and was identified by comparison of the 1 H NMR data with those published.…”

“…The compound had earlier been prepared by a different route and was identified by comparison of the 1 H NMR data with those published. [36] Similarly, 7 was obtained in 98% yield by reaction of 2 with (4-bromophenyl)lithium in the presence of an excess of AlCl 3 . Compound 7 was identified by its IR, 1 H, 13 C NMR and mass spectra.…”

“…[28,36,41,42] In an attempt to access the multibridged framework of 8 it was reasoned that the difulvene 11 might be a suitable precursor. Although 11 has been mentioned in a review article by Mueller-Westerhoff, no synthesis or characterization has been published.…”

“…Dichloromethane was dried over CaH 2 and distilled under Ar prior to use. Starting materials were either pur- [35,36] yield: 0.490 g (1.2 mmol, 76%). Recrystallization from CHCl 3 /hexane gave pure crystals suitable for an X-ray structure analysis.…”