“…Clearly, this alkylation can proceed only via formation of a conjugate base of the starting material. Various base/solvent combinations for deprotonation of semicarbazones (e.g., MeONa/DMF [25,26], Et4NOH/THF [27][28][29], NaOH/EtOH-H2O [30], t-BuOK/THF [5,[31][32][33], NaH/DMF [34], K2CO3/DMF [35][36][37], Cs2CO3/MeCN [38], tert-butylimino-tri(pyrrolidino)phosphorane/THF [39]), followed by treatment with alkylating reagents, were reported. We tested some base/solvent combinations for the alkylation of semicarbazones of aromatic aldehydes (E)-1a-c as model compounds (Scheme 2).…”