The present technology relates to a new general procedure for the reduction of sulfoxides to sulfides using [MoO2Cl2(dmf)2] as catalyst and poliols (pinacol or glycerol) as reducing agent. The products are obtained in excellent yields. It is worth to note that this new procedure uses an easily available and non-toxic reducing agent, that generates non-toxic byproducts which are easily separated from the sufide synthesized.
New and innovative aspects
The main novelty of the present method is the use of poliols (pinacol o glycerol) as reducing agent, that implies several advantages over traditional methodologies for the reduction of sulfoxides to the corresponding sulfides. Thus, clasical reducing agents for this transformation encompass sulfur-containing compounds such as thiols, hydrogen sulfide; carbodithionic, thiophosphonic or thiophosphoric acids, sulfonyl or sulfinyl chloride, disulfides, elemental sulfur (S8) and thionyl chloride. However, this methods present certain disadvantages that make necessary the development of new alternatives.
Main advantages of its use
Main disadvantages of known methods are related to reaction conditions not compatible with the presence in the molecule of sensitive functional groups. Moreover, many methods generate byproducts that are difficult to separate from the final product, making neccesary tedious and costly purification stages to obtain pure products. Furthermore, most byproducts, reducing agents and solvents are toxic and environmentally harmfull.
Nevertheless, the procedure for the reduction of sulfoxides reported in the present invention is based in the use as reducing agent of pinacol or glycerol, an easily available and easy to handle compound which generates easily removable and enviromentally friendly byproducts and allows the isolation in high yields of high purity sulfides without the need of costly and tedious chromathographic purification procedures. Moreover no inert atmosphere or organic solvents are needed, with the consequent economic and enviromental benefits.
The present invention relates to a procedure for the catalytic reduction of organic compounds that contain a sulfoxide functional group to sulfide compounds, that include a thioether functional group, by using pinacol (2,3-dimethyl-2,3-butanediol) or glycerol (propanotriol) as reducing agent in the presence of a Mo (VI) catalyst, in a solvent free reaction media, under atmospheric pressure and a temperature between 80-90 ºC using pinacol, or 170-200ºC using glycerol, generating as non-toxic and easily separable byproducts.
The technic allows the synthesis of compounds containing sulfur in their structure, that can show diverse already demonstrated propierties (drugs, pesticides, materials,…). Therefore, applications in pharmaceutical and agrochemical industries.
Intellectual property status
Current development status
Desired business relationship