Synthetic studies with carbonates. Part 10. Reactions of ethylene carbonate with some active methylene compounds catalysed by quaternary ammonium or alkali metal halides

Abstract

The reaction of ethylene carbonate (1) with pentane-2,4-dione (2) was carried out in the presence of a series of halides as catalysts. As examples, the reaction catalysed by sodium iodide gave 4-oxopentyl acetate (3), and that catalysed by tetraethylammonium chloride gave 2-methyl-2-(2-oxopropyl)-1.3-dioxolan (4), as the predominant product in high yield. Reactions with 1,3-diphenylpropane-1,3-dione (11) in place of (2) showed the same trend. However, reactions with 2-alkyl-1,3-diphenylprop-ane-1,3-diones, (20) and (25), gave no oxoalkyl esters corresponding to (3), but other types of product [(21), (22), and (26)]. In reactions with 3,3-dibenzylpentane-2,4-dione (30), which has no proton dissociable under the conditions used, were obtained 3-benzyl-4-phenylbutan-2-one (31), 2-(2-acetoxyethoxy)-3-benzyl-4-phenylbut-2-ene (32), and 2-hydroxy-ethyl acetate (33). Reaction mechanisms are discussed.

Moreover, ethyl acetoacetate (34) anddiethyl malonate (35) gave lactone derivatives, (37) and (39), respectively, but diethyl 2-acetamidomalonate (36) gave ethyl 2-acetamidobutyrate (40), in reactions with (1). Furthermore, the reactions of (1) with the diones (2) and (11) in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) gave the corresponding ethylene acetals (4) and (16), respectively.