A convenient synthetic method for 1,4-dithiins was developed using sulfur and alkynes. A rhodium complex catalyzes the addition reaction of sulfur with cyclic alkynes giving the corresponding symmetrical 1,4-dithiines under reflux conditions in 2-butanone. Unsymmetrical 1,4-dithiins are synthesized by the reaction of sulfur with dialkyl acetylenedicarboxylates in the presence of cyclic alkynes or vinyl ethers.
Key words
sulfur - 1,4-dithiins - rhodium - addition reaction - alkynes