Pyrones. IX. Synthetic approaches to the fungal metabolite phacidin and its derivatives

The synthesis of the antibiotic fungal metabolite phacidin 1 (4-methoxy-6-nonanoyl-2H-pyran-2-one-3-carboxaldehyde) and two related compounds is reported. Phacidin has been prepared in four steps from the readily available triacetic acid lactone (4-hydroxy-6-methyl-2H-pyran-2-one), while the decarbonylated derivative 2 and the bromo compound 3 have been synthesized utilizing a route based upon the condensation of the dianion of ethyl acetoacetate with a substituted 1,3-dithiane-2-carboxaldehyde.