Reactions of Sulfanyl Chlorides with Thiocamphor and Thiofenchone: WagnerMeerwein Rearrangement of an Intermediate Thiocarbonylium Ion

Abstract

The reaction of sulfanyl and disulfanyl chlorides with thiocamphor (6) in the presence of Et 3 N leads to unsymmetrical di-and trisulfanes, respectively (Schemes 2 and 4). A reaction mechanism via a thiocarbonylium ion, which is immediately deprotonated, is proposed. The formation of a minor product 10 in the absence of a base, resulting from a WagnerÀMeerwein rearrangement, is an additional evidence for the intermediacy of a thiocarbonylium ion (Scheme 3). On the other hand, the non-enolizable thiofenchone (13) reacts with sulfanyl chlorides in CH 2 Cl 2 /Et 3 N to give exclusively products with a rearranged bicyclic skeleton (Scheme 5). A WagnerÀMeerwein rearrangement of the intermediate thiocarbonylium ion is the key step. The structures of the products 10 and 14, which have rearranged bicyclic systems, have been established by X-ray crystallography.

Reactions of Chlorosulfanyl Derivatives of Cyclobutanones with Different Nucleophiles

“…The reaction of sulfanyl chlorides with S nucleophiles represents a standard method for the elongation of the S-chain in polysulfanes [48] [49]. The application of thiocarbonyl compounds as nucleophiles has been described recently [50] [51], and the reaction of thioacetic S-acid with 2 and 3 [2], as well as with a similar sulfanyl chloride [45], was already mentioned in the introduction (Scheme 1). The resulting esters were used for the synthesis of S-rich heterocycles.…”

Reactions of (1,3,3-Trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl Chloride with Some S- and O-Nucleophiles

“…The 1 H NMR spectrum of this material showed a doublet at 6.18 ppm, which is characteristic for camphen-2-yl sulfides (see e.g. 12,13 ). In addition, the 13 C NMR spectrum revealed the presence of two sp 2 -C atoms (d at 135.1 and s at 141.5 ppm).…”

Reaction of Thiofenchone or Thiochamphor with Disulfur Dichloride: Novel Formation of Tricyclic Polysulfanes

“…10 Based on an analogy to the mechanism proposed by them, tetrasulfane 4 might be formed as follows: thiofenchone 1 reacted with S 2 Cl 2 to give carbocation a, which rearranged via Wagner-Meerwein manner to afford tertiary carbocation b. Proton abstraction and subsequent cyclization gave tricyclic cation c, which finally afforded tetrasulfane 4 (Scheme 3).…”

“…We then investigated the reaction of selenofenchone 8 with diselenium dibromide to see whether a Wagner-Meerwein rearranged product would be formed. Treatment of 8 with diselenium dibromide in dichloromethane at 0 • C resulted in the formation of yellow crystals of bis(7,7-dimethyl-2-methylenebicylco[2.2.1]heptyl) diselenane (9) in 87% yield along with a small amount of triselenane (10), which was unstable and decomposed in air to give 9 and elemental selenium (Scheme 4). 11 The structure of 9 was determined by its NMR spectrum: the characteristic feature of 1 H NMR showed at 0.86 and 1.01 for methyl and 4.86 and 5.17 ppm for exo-methylene protons.…”

“…Since Majchrzak et al reported that the reaction of thiocamphor 2 with alkanesulfenyl chlorides gave sulfanes and Wagner-Meerwein rearranged products, 10 we investigated the reaction of thiocamphor 2 with S 2 Cl 2 to see whether the corresponding Wagner-Meerwein rearrangement would occur. The results are shown in Table 1.…”