A selective one-pot electrochemical thiocyanation of methoxybenzene (anisole)

A Two‐step Anodic Thiocyanation of Alkenes in Formic Acid

“…Scheme describes a mechanistic framework involving an initial electrogeneration of thiocyanogen by anodic oxidation of thiocyanate anion that undergoes hydrogen bonding by the solvent formic acid, and – as a consequence – polarization of the S−S bond. Previously it was found that acidic conditions are essential for promoting this reaction. Then a concerted (or non‐concerted) electrophilic attack by the electron‐deficient sulfur moiety of the polarized cyanogen on the alkene could take place, possibly to generate a cyano‐sulphonium ion (or an ‘open′ carbocation) intermediate.…”

“…Electrolysis was arbitrary terminated after passing 1.5 F/mol of thiocyanate salt and then 5 mmol of alkene were added to the electrogenerated thiocyanogen solution, and allowed to stir overnight at r.t. It is noteworthy that the two‐step process is essential because attempts to carry out a one‐pot reaction (at 1.25 V vs. Ag wire quasi‐reference electrode, as it was done previously for aromatic thiocyanation ) afforded low yields of products. Then the reaction mixture was filtered and treated twice with 30 ml of saturated aqueous NaCl and 30 ml of CH 2 Cl 2 .…”

“…The solvent CH 2 Cl 2 was evaporated until reaching a final volume of ∼1 ml. A sample of the residue was checked by glc and the yield of the products was determined by a calibration curve of an external standard consisting of 1‐methoxy‐4‐thiocyanatobenzene .…”

“…Anodic thiocyanation/isothiocyanation of organic compounds is somewhat limited. Recently we reported on electrochemical thiocynation of aromatic derivatives which was found to be particularly useful for methoxy‐substituted benzenes . Fotouhi and Nikoofar reported on anodic thiocyanation of nitrogen‐containing aromatic and heteroaromatic compounds in methanol.…”

Recent advances in photochemical and electrochemically induced thiocyanation: a greener approach for SCN-containing compound formation

“…Gitkis et al examined the straightforward one-pot electrochemical-induced thiocyanation of methoxy benzene (anisole) 115, which is highly regioselective in glacial acetic acid for the construction of 1-methoxy-4-thiocyanatobenzene 116. 49 The yield of the product increases to over 80% at room temperature under the specified optimum conditions, and no detectable para -thiocyanogen owing to thiocyanogen polymerization is observed. Furthermore, controlled potential electrolysis is more effective than constant-current electrolysis in the synthesis of 1-methoxy-4-thiocyanatobenzene 116 ( Scheme 40 ).…”