Ethyl α-(Triphenylphosphoranylidene)amino-β-ferrocenylacrylate as a Starting Material for [2+2] Cycloadditions, Including the Aza-Wittig Reaction

• Published in: European journal of organic chemistry 2004-02, Vol.2004 (4), p.717-723
• Main Authors: Csámpai, Antal, Túrós, György, Kudar, Veronika, Simon, Kálmán, Oeynhausen, Hendrik, Wamhoff, Heinrich, Sohár, Pál
• Format: Article
• Language: English
• Subjects: Nitrogen heterocycles; Oxygen heterocycles; Sandwich complexes; Structure elucidation
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200300511

Ethyl α‐(triphenylphosphoranylidene)amino‐β‐ferrocenylacrylate, synthesized from the corresponding azide, was treated with a few selected electrophilic agents potentially capable of undergoing the aza‐Wittig reaction. The transformations with aroyl chlorides and phenylisocyanate afforded a series of novel 4‐(ferrocenyl)methylidene‐2‐aryloxazolones. On treatment of the phosphorimino compound with DMAD two competitive reactions took place on the C=C and N=P bonds, giving rise to a novel amino(ferrocenyl)butadiene and a ferrocenyl‐substituted aza‐pentadienylphosphorylide, respectively. The parent azidoferrocenylacrylate underwent the expected 1,3‐dipolar cycloaddition with DMAD, resulting in a triester of a (ferrocenyl)vinyl‐substituted v‐triazoletricarboxylate suitable for a variety of further heterocyclic syntheses. The structures of the new compounds were determined by IR and NMR spectroscopy, mass spectrometry, and X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)