Electrochemical Preparation of Aryl Mom Ethers

Abstract

In organic synthesis, methoxymethyl (MOM) ethers are frequently used as acid-labile protecting group [1] or leaving group in aryl cross-coupling reactions [2]. Their preparation commonly involves MOM chloride, a carcinogenic liquid with high vapour pressure which should be avoided as much as possible [3]. Therefore, we started to synthezise aryl MOM ethers without the use of MOM chloride by application of sustainable electrosynthetic methods [4]. Anodic decarboxylation of 2-aryloxy acetic acids under non-Kolbe conditions and trapping of the corresponding cation with methanol gives the desired MOM ethers (Figure 1). Indeed, this pathway is described for few aliphatic α-alkoxyacetic acids [5] and unsubstituted phenoxyacetic acid [6], but scope of this transformation to prepare substituted aryl MOM ethers has not been investigated so far. We now present our studies on the preparation of substituted aryl MOM ethers by anodic decarboxylation using an undivided cell setup. A wide range of substituents on the phenyl moiety is tolerated, giving access to valuable protected phenols [7].