Synthesis of Intermediates of AB-CHMINACA metabolite M2

The key intermediate 5 of the AB-CHMINACA metabolite M2 was synthesized through a sequence of alkylation, hydrolysis, and amide coupling reactions, affording a moderate yield. In particular, the compound 2 and its regioisomer 3 were distingushed by Nuclear Overhouse Effect (NOE) experiments. In the NOE analysis, compound 3 show no NOE correlation between the methylene (CH2) and the aromatic proton, whereas compound 2 exhibited a pronounced NOE effect. The unambiguous identification of compound 2 was crucial for the synthesis of the AB-CHMINACA metabolite M2. The resulting sy nthetic metabolite will serve as a reference standard compound for the detection of illicit drugs.