Synthetic applications of electrochemically produced α‐methoxyamides. Part 2. Oxidation of hydroxyproline derivatives

Abstract

Abstract The electrochemical methoxylation of N ‐acetyl‐4‐hydroxyproline esters has been investigated. Both the free alcohol 3 and the corresponding 4‐acetoxy derivative 4 as well as the cis ‐4‐acetoxyproline 17 are methoxylated anodically preferentially at C(5), giving a mixture of stereoisomeric methoxy compounds. These mixtures can be used for further substitution as exemplified by the allylation of the methoxylated 4‐acetoxy derivatives, giving substitution products preferentially trans to the acetoxy group although with low selectivity. The low selectivity is discussed in terms of kinetic vs. thermodynamic control.