The effect of N-acyl and N-sulfonyl groups on the anodic methoxylation of piperidine derivatives

• N-acyl (-CHO, -COMe, -COOMe, -COPh, -COCF3) and N-sulfonyl (-SO2Me, -SO2Ph, -SO2 (p-tolyl) piperidines were studied by cyclic voltammetry.
• Methoxylation of N-acyl and N-sulfonyl piperidines was performed at various anodes (graphite, carbon felt, glassy carbon (GC) Pt and PbO2) and electrolytes (But4NClO4, Et4NBF4, Et4NOTs), using constant current electrolysis.
• Methoxylation on graphite/Et4NOTs favored formation of α-monomethoxylated products.
• Methoxylation on graphite/Et4NBF4 favored the formation α,α'-dimethoxy derivatives.

N-acyl (-CHO, -COMe, -COOMe, -COPh, -COCF3) and N-sulfonyl (-SO2Me, -SO2Ph, -SO2 (p-tolyl) piperidines were synthesized and studied by cyclic voltammetry. Their anodic methoxylation was performed at various anodes (carbon rod, carbon felt, glassy carbon, Pt and PbO2), in the presence of different electrolytes (But4NClO4, Et4NBF4 and Et4NOTs), applying a current density of 20 mA cm−2. Methoxylation on graphite with Et4NOTs favored the formation of α-monomethoxy products whereas in the presence of Et4NBF4, the α,α'-dimethoxy derivatives become predominant in selected cases.

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