N-Substituted 1,4,5,6-tetrahydropyridazines ((3) under bar) can be prepared in a one pot procedure from a hydrazine (1) under bar) and 2,5-dimethoxytetrahydrofuran ((2) under bar) using NaBH4 in aqueous-THF acidic medium in fair yields. Variable amounts of two side products are also formed: hexahydropyridazines (5) under bar, likely produced by a route other than the direct reduction of (3) under bar and 1-aminopyrrolidines (4) under bar. A direct reduction-N-reductive ethylation of (3) under bar could be achieved in AcOH with NaBH4.
