Mercaptals alkylation

AUehyde synthesis. The carbanion generated from this reagent (I) reacts with an alkyl halide to give an aldehyde dimethyl mercaptal S-oxide (2). This product is easily... 

Hydroxydithiocinnamic acids (1) can be converted into the monosalt by treatment with tetra-n-butylammonium hydrogen sulfate and NaOCHj, which on alkylation gives the dithioesters (2) in high yield. Mercaptals (3) can be prepared in 70-88% yield by treatment of (2) with thallous ethoxide (2, 407 411) and an alkyl halide. 

Methylthio-l,2-dithiolium perchlorates may be obtained directly from keten mercaptals, for example (31), by the action of phosphorus pentasulphide and subsequent treatment of the insoluble residue with perchloric acid. Similar treatment of /3-keto-amides (32) yields 3-arylimino-l,2-dithiole perchlorates (27 R = Ar, X = CIO4). The method succeeds with amides (32 R = alkyl) and thus serves as a route to the previously inaccessible 5-alkyl-l,2-dithiol-3-imines. Demethylation of 3-methylthio-5-phenyl-l,2-dithiolium cation, to give 3-phenyl-l,2-dithiole-3-thione, occurs when the iodide is heated in xylene. 

Thioisobiurets, 0- S-alkyl migration 16, 646 Thioketals s. Mercaptals y -Thioketocarboxylic acid esters... 

Reactions of Formaldehyde with Mercaptans. Reactions of formalde-ifvde with thio-alcohols or mercaptans are similar in many respects to those encountered with alcohols. According to Posner ", mercaptals or methylene dithiols are formed in a two-step lection, as indicated by the equations shown below in which the R of RSH stands for an alkyl, aralkyl or aryl radical. 

---