Crossover Point between Dialkoxy Disulfides (ROSSOR) and Thionosulfites ((RO)₂SS):  Prediction, Synthesis, and Structure

Abstract

Isomeric preference between cyclic dialkoxy disulfides and thionosulfites is governed by the ring size of the heterocycle. Rings smaller than seven atoms prefer the thionosulfite connectivity, whereas larger rings or acyclic analogues favor the unbranched dialkoxy disulfide structure. Density functional calculations were employed to predict the crossover point at which both constitutional isomers are of comparable stability. Follow-up synthesis provides the previously unknown eight-membered ring dialkoxy disulfide 14 and seven-membered ring thionosulfite 15 from the same reaction. X-ray crystallography for all but one of the reaction products and complementary NMR analysis furnishes insights into both solid-state and solution conformations. A long-standing issue regarding the concerted vs catalyzed isomerization pathway between XSSX and X(2)S=S has been addressed for X = RO and shown to be acid dependent.

Sulfur monochloride in organic synthesis

“…126 Detailed study of this reaction has shown that dialkoxy disulfide 184 in all cases is the major product; however, upon the introduction of triethylamine into the reaction mixture, other cyclic products Ð seven-membered thiosulfite 186 and 16-membered dimer 187 Ð can also form (Scheme 94).…”

Disulfur Dichloride (S2Cl2)

“…(D) Reaction of a diol with S 2 Cl 2 resulted in the first example of a stable and fully characterized cyclic dialkoxy disulfide under mild conditions. 11 (E) S 2 Cl 2 was reacted with 1,7-s-hydrindacenedione dioximes leading to the first example of bis [1,2,3]dithiazolo-s-indacene. 12 In this example, S 2 Cl 2 has also been found as a chlorinating agent.…”

Unsymmetrical polysulfidation via designed bilateral disulfurating reagents

“…2a ). Dialkoxydisulfide 28 , 29 and diaminodisulfide 30 – 32 have been investigated as sulfur transfer reagents since 1970s. However, unsymmetrical polysulfidation with disulfanyl motif has never been achieved owing to the sharp contradiction raised by sequential and selective cleavage of dual S-O(N) bonds.…”