Carbonyl sulphide generation

Transient Species.—Pioneering studies by Johnson and co-workers have shown that monomeric thioformaldehyde is generated when methane reacts with small sulphur-containing molecules, such as carbon disulphide, carbonyl sulphide, or hydrogen sulphide, at low pressure in a radio-frequency discharge tube. On the basis of these results, Johns and Olson prepared thioformaldehyde, under slightly different conditions, from dimethyl disulphide in the presence of sulphur hexafluoride. The reaction path suggested was ... 

The addition of dimethyl sulphide to a,/3-unsaturated carbonyl compounds in the presence of TMSOTf generates highly reactive 3-trialkylsilyloxyalk-2-enylenesulfonium salts, which permits the introduction of a wide variety of nucleophiles at the -position as well as a-functionalization. ... 

There have been a number of reports on the photochemical reaction between diazo-compounds and sulphides to form either stable or transient ylides. lllger et al. reported the isolation of a series of ylides from the reaction of dimethyl sulphide with substituted diazomethanes, such substituents being carbonyl, sulphonyl, or phosphoryl groups. Ando et of. described the reaction of diazo dimethyhnalonate with a series of sulphides but found that the yields of ylides varied considerably, much more so than for the thermal reaction, with the nucleophilicity of the sulphide. For example, dimethyl sulphide afforded an 88% yield of ylide (6a) while diphenyl sulphide afforded a 12% yield of ylide (6b). Repetition of the reaction with dimethyl sulphide but in the presence of cyclohexene indicated that the sulphide was about six times as reactive as the olefin toward the photochemically generated carbene. These reactions aU were assumed to occur by conversion of the diazo-compound into a singlet carbene, which attacked sulphur. However, it was found that (6a) also could... 

---