Studies in the synthetic utility of the dianion of B-ketoesters

Some of the reactions of the dianion of β-ketoesters were investigated. The dianion of methyl acetoacetate (132), prepared by sequential reaction of methyl acetoacetate with sodium hydride and n-butyllithium, was reacted with a variety of aldehydes and ketones to give δ-hydroxy-β-ketoesters (150) in moderate yield. The aldol products 150 derived from aromatic aldehydes and ketones were found to be thermally unstable and were converted to trimethylsilyl ether derivatives for characterisation purposes. The acylation of dianion 132 was also investigated, and a modified procedure developed which allowed the preparation of β,δ-diketoesters in fair yield. When aromatic esters were employed as acylating agents, the product isolated was found to be a mixture of diketoester and diketoacid. The reaction of dianion 132 with nitriles was briefly investigated, and shown to be a feasible method of producing γ-unsaturated δ-amino- β -ketoesters. Finally, with dihaloalkanes, dianion 132 gave a mixture of cyclic alkylated products and bis- β -ketoesters. Procedures for the optimising of the yields of each of these classes of compounds were developed.Science, Faculty ofChemistry, Department ofGraduat