An Efficient Synthesis of Novel Benzo-Fused Macrocyclic Dilactams

A facile synthetic approach was adopted towards the synthesis of benzo-fused macrocyclic lactams 2a–2g via the base-catalyzed condensation reaction of 2,2′-[alkanediylbis(oxy)]bis[benzaldehydes] 3a–3c with N,N′-substituted bis[2-cyanoacetamide] derivatives 7a–7c (Scheme 2). The latter compounds were obtained by the reaction of the appropriate diamines 6a–6c with ethyl 2-cyanoacetate (4). Attempts to prepare the oxaaza macrocycles 2 by alternative pathways were also investigated. The novel pyrazolo-fused macrocycles 13a and 13b were obtained in 48 and 52% yield, respectively, upon treatment of 2d and 2g with NH2NH2⋅H2O at 100°