Sulfurization of Thiones: 2,2,4,4-Tetramethyl-3-thioxocyclobutanone

✍ Scribed by Huisgen, Rolf ;Rapp, Jochen ;Huber, Helmut

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 759 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970730

✦ Synopsis

Abstract

By treatment with elemental sulfur and a catalytic amount of sodium thiophenolate in acetone at room temp., the title compound 9 is converted to the bis‐spiro derivatives of 1,2,4,5‐tetrathiane, 13, and 1,2,3,5,6‐pentathiepane, 14. The initial attack by the phenyl oligosulfide anion takes place at the C‐atom of the thiocarbonyl group. There is ^13^C NMR evidence for the twist conformation 15 of the tetrathiane ring; dynamic ^1^H NMR led to Δ__G__^≠^ = 15.9 ± 1.0 kcal mol^−1^ for the enantiomerization. For the pentathiepane 14, twelve coalescence phenomena in the ^1^H and ^13^C NMR spectra point to Δ__G__^≠^ = 13.4 ± 0.2 kcal mol^−1^; the process is interpreted as a stereomutation on the pseudorotation circuit for twist‐chair and chair. The MS of 13 reveals a diversity of fragmentation patterns with several “thiologous” sequences. By prolonged treatment with the thiophenolate catalyst, 13 and 14 are converted to a γ‐butyrodithiolactone 36 in a Baeyer‐Villiger type reaction.