Zur Reaktion von Triafulvenen mit Isonitrilen. Eine einfache Synthese von diphenylsubstituierten funktionalisierten Cyclobuten-Derivaten und deren Folgeprodukten

Reaction of Triafulvenes with Isonitriles. A Simple Synthesis of Diphenyl-Substituted Functionalized Cyclobutene Derivatives and Related Products The reactions of triafulvenes 1a-e with a series of isonitriles 2a-e are investigated. From 1a-c in aprotonic media 2-methylenecyclobutene-1-one imines (3a-h) are formed in good yields, which are characterized by spectral data, hydrolysis to 2-methylenecyclobutene-1-ones 4 and independent synthesis of a selected hydrolysis product (4c). In protonic media the products 3, e.g. 3b,e, incorporate a solvent molecule to give N-alkyl pyrrols 7,8. Triafulvenes 1d and 1e give other types of products, whose structures are likely to be 12-15. A mechanism for the reaction of triafulvenes with isonitriles is presented, in which an allenic ketene intermediate plays a central role for the formation of all products obtained.