Synthese und Eigenschaften von 3-Acylmethylen-2-(2-hydroxy-1-alkenyl)-1-phenylcyclopropen, einer neuartigen Klasse von stabilisierten Triafulvenen

Abstract

Triavulvenes of type 9 are obtained by reaction of dichloro(phenyl)-cyclopropenylium cation 7 with two equivalents of silyl enol ethers 8. They are characterized by means of their spectroscopic data and by X-ray analysis of 9c as cyclic 7-hydroxy-2,4,6-heptatrien-1-one systems with intramolecular H-bonding (type 10) representing a new type of stabilized methylenecyclopropenes. Similar compounds are formed by reaction of 7 with 4-methoxytoluene and 2-methoxynaphthalene (12, 15) or with dimedone (13). The cyclopropenone 16 is obtained as main product of the 1:1 reaction of 7 and 8a, it isomerizes thermally to give the a-pyrone 17.