Further reactions of t-butyl 3-oxobutanthioate and t-butyl 4-diethyl-phosphono-3-oxobutanthioate : Carbonyl coupling reactions, amination, use in the preparation of 3-acyltetramic acids and application to the total synthesis of fuligorubin A.

The use of t-butyl-3-oxobutanthioate (1) and t-butyl 4-diethylphosphono-3-oxobutanthioate (2) for the preparation of homologated derivatives suitable for amination in the presence of silver (I) trifluoroacetate to afford the corresponding β-ketoamides is discussed. In particular Wadsworth-Emmons coupling reactions of (2) with various carbonyl compounds gave good yields of E-substituted products. Many of the β-ketoamides were shown to be suitable precursors for 3-acyltetramic acids using a Dieckmann cyclisation with tetra-n-butyl ammonium fluoride as the cyclising base. These new reactions were applied to the total synthesis of the polyene 3-acyltetramic acid fuligorubin A.