文摘
This article reports the synthesis of some new spiro-β-lactams bearing an indeno[1,2-b]quinoxaline ring system, prepared by a [2 + 2] cycloaddition of ketenes with imines derived from 11-H-indeno[1,2-b]quinoxalin-11-one. The structures of newly synthesized spiro-β-lactams 2a–i and 3a-i were characterized by FT-IR, 1H NMR, 13C NMR, mass spectrometry and elemental analyses. The relative stereochemistry of spiro-β-lactams 2a and 3a was determined unequivocally by X-ray crystallographic studies.