Derivatives of Cp2TiCl2 continue to be in the focus of contemporary research as efficient reagents and catalysts, as a promising class of cytostatic agents and in their own right. To further investigate and improve these properties it is essential to access as yet unexplored functionalized titanocenes. We have devised an easy and efficient synthesis strategy towards aniline-functionalized titanocene complexes 2 with different substitution patterns. A crucial factor for the success of this synthetic route is the choice of the amino protecting group as its cleavage has to proceed under conditions that are tolerated by the electrophilic titanocene moiety. Starting from the novel key compound 2 a broad variety of diversely functionalized titanocenes can now be made accessible. Azide-functionalized titanocenes 3 were synthesized via one-pot diazotization-azidation and subsequently applied in Ru-catalyzed or strain-driven 1,3-dipolar cycloaddition reactions. Furthermore we were able to synthesize the first examples for titanocene containing azo compounds 6. The isolation of arenediazonium-functionalized titanocenes 7 (as tetrafluoroborate salts) is of special relevance as they present an interesting building-block for further modification via diazonium chemistry (e.g. Schiemann reaction, Meerwein reaction, Pd-catalyzed cross coupling reactions).

Towards molecular diversity with functionalized titanocenes

253rd National Meeting (2017)

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