Department of Organic Chemistry, Chemical Institute, Aarhus University, DK-8000 Aarhus C, Denmark
Abstract:
By use of the ion pair extraction technique, tetrabutylammonium salts of acetylacetone, benzoylacetone, and dibenzoylmethane were reacted with carbon disulphide to give salts of dithioacids. Alkylation gave dithioesters and ketene mercaptals. A simple procedure for the preparation of 2-diacylmethylene-1,3-dithietanes was found. Cyclisation reactions of some acetylacetone derivatives gave a 1,3-dithiolane, a mercaptothiophene, and a 2.3-b] thienothiophene. Allylic ketene mercaptals derived from acetone, cyclohexanone, acetylacetone, benzoylacetone, and dibenzoylmethane rearranged to α-allyl-dithioesters. Inversion of the migrating allyl group was observed when the ketene mercaptal had a vinylic hydrogen; otherwise retention was found. 3-(Crotylthio-, methylthio-)methylene] acetylacetone underwent decomposition at 170° to methyl, 1-methyl-allyl sulphide and the “desaurin”: 2,4-bis-(diacetyl-methylene)-1, 3-dithietane. By-products in syntheses of the dithioesters and ketene mercaptals included trithiocarbonates, alkylated β-diketones, and compounds formed by reactions of the solvent (CH2Cl2) with β-diketones or their carbon disulphide adducts (1,3-di-thietanes).