A new route to L‐homoglutamine (L‐α‐aminoadipamic acid) derivatives is presented via preferential KMnO4oxidation in acidic media of the e‐methylene group in H‐L‐Lys(Z)‐OH and Z‐L‐Lys(Z)‐OH. The main oxidation products are 5‐benzyloxy‐carbonylcarbamoyl‐2‐aminopentanoic acid (H‐L‐Aad(NHZ)‐OH) 2 and 5‐benzyl‐oxycarbonylcarbamoyl‐2‐benzyloxycarbonylaminopentanoic acid (Z‐L‐Aad(NHZ)‐OH)10, respectively, in which the intact benzyloxycarbonyl protection is now attached to the nitrogen atom of the δ‐amide group. The accompanying hydrolysis of the labileN‐protected amide group and the continuing oxidation, however, diminish the quantity of2and10in the reacting mixture. Therefore, to obtain fair yields of these products, useful in peptide synthesis, involving homoglutamic acid and homoglutamine (H‐L‐Aad(NHZ)‐OH and Z‐L‐Aad(NHZ)‐OH contain carboxylic groups in differential form) a compromise must be reached and the oxidation process stopped at the right moment. Besides the desired oxidation product involving the transformation of the e‐methylene group into the carbonyl group, a number of side products formed by oxidation of the α‐carbon atom (derivatives of δ‐aminovaleric acid) and e, α‐c