Monocyclic β-lactams commonly referred to as azetidin-2-ones and their derivatives have been extensively explored for their wide biological applications. The present study demonstrates a simple and efficient synthesis of monocyclic β-lactam derivatives via Staudinger reaction, well characterized by FT-IR, ¹H, ¹³C-NMR, mass spectral data and elemental analysis. We also confirmed the formation of highly substituted 1,3-oxazin-4-ones under the same reaction condition