Synthesis of [Ethylene-1-(η5-4,5,6,7-tetrahydro-1-indenyl)-2- (η5-4‘,5‘,6‘,7‘-tetrahydro-2‘-indenyl)]titanium Dichloride, the Elusive Isomer of the Brintzinger-Type a nsa-Titanocenes

We present a short synthesis of 1-(2-indenyl)-2-(3-indenyl)ethane (5) and a method for its conversion to the ansa-metallocene [ethylene(η5-inden-1-yl)(η5-inden-2-yl)]titanium dichloride (13). The synthetic strategy applied to prepare bisindene 5 relies on the efficient alkylation of 2-(phenylsulfony...

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Bibliographic Details
Published in:Journal of organic chemistry 2003-10, Vol.68 (22), p.8447-8452
Main Authors: Kelly, Patrick A, Berger, Gideon O, Wyatt, Justin K, Nantz, Michael H
Format: Article
Language:English
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Summary:We present a short synthesis of 1-(2-indenyl)-2-(3-indenyl)ethane (5) and a method for its conversion to the ansa-metallocene [ethylene(η5-inden-1-yl)(η5-inden-2-yl)]titanium dichloride (13). The synthetic strategy applied to prepare bisindene 5 relies on the efficient alkylation of 2-(phenylsulfonyl)indane followed by HMPA-assisted E1cB-elimination of phenylsulfinate. This tandem sequence circumvents the predisposition of indene to undergo C(1)-alkylation and enables access to C(2)-substituted indenes. The key step in the synthesis of the title ansa-titanocene (4) features a previously unreported equilibration step to generate the bis(indenide anion) of 5. Complexation with TiCl4·(THF)2 followed by hydrogenation of the product metallocene furnishes ansa-titanocene 4.
ISSN:0022-3263
1520-6904
DOI:10.1021/jo034975o