Reaction of 1—3-(η-acryloyl)tricarbonylferrate with acyl halides giving 1 : 1 adducts, the 2-acyloxy-1,1-dicarbonyl-1-halogenoferracyclopent-2-en-5-onates

Abstract

(1—3-η-Acryloyl)tricarbonylferrate (1) reacts with the acyl halides in methylene dichloride at 0 °C to afford unexpected 1 : 1 adducts, which have been deduced to be novel 2-acyloxy-1,1-dicarbonyl-1-halogenoferracyclopent-2-en-5-onates (3a)—(3e). Complex (3a; R = Me, X = Cl) reacts with 2 mol equivalents of PMe₂Ph to give the bis(dimethylphenylphosphine)ferracyclopentenone (4) by co-ordination of the two dimethylphenylphosphines and dissociation of both the halide ion and the carbonyl group of the enol ester in (3a). The reaction of complex (3a) with SFO₂(OMe) gives 2-acyloxy-1,1,1-tricarbonylferracyclopentenone (5) by the displacement of the halide ion with CO. A reaction mechanism for formation of (3)via(η³-acyloxyvinylcarbene)tricarbonyliron is proposed.