1,3-Dithiolan-2-ones have been obtained by reaction of 1,3-dithiolane-2-thiones and epoxides in the presence of HBF4·Et2O. The reactions, carried out in anhydrous CH2CL2 at 0–5 °C→room temperature (Procedure A) or in anhydrous chlorobenzene at 0–5-→80 °C (Procedure B), gave product yields of 63–95%. By Procedure B it was also possible to isolate the intermediates 1-oxa-4,6,9-trithiaspiro[4.4]nonanes in good yields (66–85%). Reaction pathways are proposed.
A new method for the synthesis of 1,3-oxathiolan-2-ones has been developed. When oxiranes were allowed to react with sulfur in the presence of a catalytic amount of sodium hydride under pressurized carbon monoxide, the three-component coupling of oxiranes, sulfur, and carbon monoxide smoothly proceeded to give the 1,3-oxathiolan-2-ones in moderate to good yields. The reaction proceeded with a high
An equimolar reaction of 2-hexyloxirane with carbon disulfide in hexane was run in the presence of triethylamine under 800 MPa at 100 °C for 20 h, and gave 63% of 4-hexyl-1,3-dithiolan-2-one (3a), 21% of 4-hexyl-1,3-dithiolane-2-thione (1a) and 5% of 5-hexyl-1,3-oxathiolan-2-one (4a). Hexane, benzene, and diisopropyl ether were good solvents for the reaction. The reaction of a variety of oxiranes with
that 1b and 2-hexylthiirane (4b) are produced in the first stage of reaction, and that 2b is then formed by the reaction of 1b or 4b with carbondisulfide. In reactions of a variety of oxiranes with carbondisulfide, 1,3-dithiolane-2-thiones were obtained in high yields under 800 MPa at 100 °C within 20 h. Concerning the effect of substituents in oxiranes, the selectivity for product 2b is in the decreasing