An Odorless 1,3-Propanedithiol Equivalent

3-(1,3-Dithian-2-ylidene)-2,4-pentanedione (1) is an odorless 1,3-propanedithiol equivalent and it reacts with aldehydes or aliphatic ketones to afford the corresponding 1,3-dithian derivatives. These reactions don’t need any organic solvents and successfully proceed only by warming the mixture of 1 and carbonyl compounds in concentrated hydrochloric acid at 60 °C. 1,3-Dithianations using aliphatic aldehydes give excellent results, while the yields are decreased when aromatic aldehydes having strong electron-withdrawing groups are used. And more, in a case using of aromatic ketones, it takes a long time to complete the 1,3-ditianation. Thus, 1,3-ditianation for the mixture of aldehydes and ketones is aldehyde chemoselective and ditioacetalized aldehydes are formed as a sole product. The treatment after the reactions is carried out only a very faint thiol smell, so 1 is an efficient 1,3-propanedithiol equivalent.