Synthesis of Bis(spiroazetidin-2-ones) Containing Cyclopropane, Cyclobutane or Cyclopentane Fragments via the Reaction of Alicyclic Reformatsky Reagents with Terephthalaldehyde Diimines

The reaction of Reformatsky reagents, obtained from methyl-1-bromocyclopropane-, 1bromocyclobutane-, and 1-bromocyclopentanecarboxylates and zinc, with diimines, derived from terephthalaldehyde, was studied. As a result, a series of novel bis(spiroazetidin-2-ones) was synthesized. It was found that compounds with а cyclopropane fragment are formed in lower yields than cyclobutane and cyclopentane analogues, and ortho-substituents in the aryl moiety at the nitrogen atoms of the substrate hinder cyclization in this case. The structures of the obtained compounds were confirmed by IR, 1H and 13C NMR spectroscopy, elemental analysis, and X-ray diffraction analysis.