Crossover point between dialkoxy disulfides (ROSSOR) and thionosulfites ((RO)2S=S): prediction, synthesis, and structure

Eli Zysman-Colman; Neysa Nevins; Nicolas Eghbali; James P Snyder; David N Harpp

doi:10.1021/ja0559395

Crossover point between dialkoxy disulfides (ROSSOR) and thionosulfites ((RO)2S=S): prediction, synthesis, and structure

J Am Chem Soc. 2006 Jan 11;128(1):291-304. doi: 10.1021/ja0559395.

Authors

Eli Zysman-Colman¹, Neysa Nevins, Nicolas Eghbali, James P Snyder, David N Harpp

Affiliation

¹ Department of Chemistry, McGill University, Montreal, Quebec, Canada H3A 2K6.

PMID: 16390159
DOI: 10.1021/ja0559395

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.