Ferrocenoindenes display planar chirality and thus represent valuable ligands for asymmetric catalysis. Here, we report on the synthesis of novel 3-(1,1-dibromomethylene)ferroceno[1,2-a]indene, ( Z)-3-(1-bromomethylene)-6-iodoferroceno[1,2-a]indene, and benzo[5,6-f]ferroceno[2,3,a]inden-1-one. Any application-oriented design of chiral catalysts requires fundamental knowledge about the ligands involved, not only in terms of atom-connectivity, but also in terms of their three-dimensional structure and steric demand. Therefore, the crystal structures of 2-ferrocenylbenzoic acid, ferroceno[1,2-a]indene, and ( Z)-3-(1-bromomethylene)-6-iodoferroceno[1,2-a]indene have been determined. The bond-lengths that can be retrieved therefrom also allow for an estimation of the reactivity of the aryl-iodo, bromo-methylidene and dibromomethylidene moieties.
References
[1]
Zanello, P. Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science; Togni, A., Hayashi, T., Eds.; VCH: Weinheim, Germany, 1995; pp. 317–430.
[2]
Barlow, S.; O’Hare, D. Metal-metal interactions in linked metallocenes. Chem. Rev. 1997, 97, 637–669, doi:10.1021/cr960083v.
Gonsalves, K.E.; Chen, X. Synthesis and characterization of ferrocene-containing polymers. In Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science; Togni, A., Hayashi, T., Eds.; VCH: Weinheim, Germany, 1995; pp. 497–530.
[7]
Schottenberger, H.; Reussner, J.; Buchmeiser, M.; Neissl, W.; Elsner, O.; Angleitner, H.; Ernst, E. Metallocenes and Their Manufacture and Use in Polymerization of Olefins. Eur. Pat. App. 0673946 A2, 27 September 1995.
[8]
K？llner, C.; Pugin, B.; Togni, A. Dendrimers containing chiral ferrocenyl diphosphine ligands for asymmetric catalysis. J. Am. Chem. Soc. 1998, 120, 10274–10275, doi:10.1021/ja981137g.
[9]
Schnyder, A.; Hintermann, L.; Togni, A. Starke einflüsse der elektronischen struktur auf die enantioselektivitat in der rhodiumkatalysierten hydroborierung rnit neuen, pyrazolyl-haltigen ferrocenylliganden (in German). Angew. Chem. 1995, 107, 996–998, doi:10.1002/ange.19951070820.
[10]
Togni, A. Planar-chirale ferrocene: Synthesemethoden und anwendungen (in German). Angew. Chem. 1996, 108, 1581–1583, doi:10.1002/ange.19961081307.
[11]
Spindler, F.; Blaser, H.-U. The highly enantioselective hydrogenation of N-diphenylphosphinyl-ketimines with cationic Rh ferrocenyldiphosphine catalysts. Adv. Synth. Catal. 2001, 343, 68–70, doi:10.1002/1615-4169(20010129)343:1<68::AID-ADSC68>3.0.CO;2-G.
Mayr, B.; Schottenberger, H.; Elsner, O.; Buchmeiser, M.R. Separation of planar chiral ferrocene derivatives on β-cyclodextrin-based polymer supports prepared via ring-opening metathesis graft-polymerization. J. Chromatogr. A 2002, 973, 115–122, doi:10.1016/S0021-9673(02)01197-4.
[14]
Elsner, O. Verknüpfung und Anellierung von Intervalenzf？higen Ferrocenderivaten (in German). Ph.D. Thesis, University of Innsbruck, Innsbruck, Austria, 1995.
Mueller, A.G.; Schottenberger, H.; Laus, G.; Wurst, K. Crystal structure of bis(ferroceno[2,3]-inden-1-yl)dimethylsilane, Si(CH3)2[Fe(C5H5)(C12H8)]2. Z. Kristallogr. NCS 2004, 219, 497–498.
[17]
Cais, M.; Modiano, A.; Raveh, A. A novel approach to the synthesis of the benzopentalene system. J. Am. Chem. Soc. 1965, 87, 5607–5614, doi:10.1021/ja00952a017.
[18]
Mooney, A.; Corry, A.J.; O’Sullivan, D.; Rai, D.K.; Kenny, P.T.M. The synthesis, structural characterization and in vitro anti-cancer activity of novel N-(3-ferrocenyl-2-naphthoyl) dipeptide ethyl esters and novel N-(6-ferrocenyl-2-naphthoyl) dipeptide ethyl esters. J. Organomet. Chem. 2009, 694, 886–894, doi:10.1016/j.jorganchem.2008.09.064.
[19]
Sheldrick, G.M. SHELXS-86: Program for Crystal Structure Solutions; University of G？ttingen: G？ttingen, Germany, 1986.
[20]
Sheldrick, G.M. A short history of SHELX. Acta Crystallogr. 2008, A64, 112–122.
