Sommelet oxidation synthesis

The Sommelet reaction, also known as the Sommelet oxidation, is the oxidation of benzyl halides (1) to the corresponding aldehydes (3) using hexamethylenetetramine (HMTA) followed by hydrolysis of the hexaminium salt 2.1-3 This reaction is closely related to the Delepine amine synthesis, the Duff aldehyde synthesis, and the Krtihnke reaction (see Section 7.10.3). 

Oxidation of the aldehyde was not used earlier because of the difficulty of obtaining the aldehyde, which is now readily available by the Sommelet synthesis from 3-thenyl bromide. Campaigne and LeSuer 7 also used alkaline permanganate as the oxidizing agent, but the yields decreased to 40-60%. The present procedure gives an over-all yield from 3-methylthiophene of about 45%. 

Formylbenzenesulfonamide has been prepared by chromic acid oxidation of -toluenesulfonamide, the Sommelet reaction on p-chloromethylbenzenesulfonamide, and by the Stephen reduction of j -cyanobenzenesulfonamide. The present method provides a general procedure for the synthesis of substituted aromatic aldehydes as illustrated in Table I. 

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