A STUDY OF THE REACTIVITY OF TRICARBONYL(VINYLKETENE)IRON(0) COMPLEXES TOWARDS ALKYNES

Alkynes add to tricarbony](vinytketene)iron(0) complexes to generate s table 1:1 adducts, the structures of which were determined by an X-ray crystal structure analysis of the adduct formed from henyl-3-iso-prop yl-1-oxapenta-1,2,4-triene)iron(0) and dimethyl acetylenedicarboxylate . Addition of unsymmetrical alkynes is regioselective and the regioche mistries of the adducts isolated from these reactions were determined by X-my crystal structure analyses of the products derived from but-3- yn-2-one and rt-butyl-5-phenyl-1-oxapenta-1,2,4-triene)iron(0), and of the structurally modified product derived from diethylpropynylamine a nd enyl-3-iso-propyl-1-oxapenta-1,2,4-triene)iron(0). Thermolysis of t he adducts leads to either cyclopentenediones or phenols and its outco me is dependent on the electronic properties of the carbon-1 substitue nt of the adduct. The phenols may be synthesised directly and regiosel ectively from tricarbonyl(vinylketene)iron(0) complexes and the approp riate alkynes.