Electrochemical alkylation of Schiff bases

Alkylation of N-(hydroxyethyl) benzylidineimine, the Schiff base formed from benzaldehyde and ethaolamine under electrochemical conditions mediated by Pb(II)/Pb(O) redox system has been reported. Cathodically (Pt) generated Pb(O) from PbBr2 reacted with allyl bromide to form allyl lead bromide in THF, in an undivided cell. Tetrabutylammonium bromide was the electrolyte. The anode was aluminium sheet (Sacrificial) which generated AlBr3 which by complexation with the nitrogen of the Schiff base, catalysed the addition of the organometallic compound to the C-N double bond, to yield, on work up, 1-phenyl-N-(hydroxyethyl) but-3-enylamine. Several side products have been identified. Conditions for optimisation of yield and effective work - up have been developed. The potential application of this reaction for the asymmetric synthesis of amines has been brought out.