Background: 2-Azetidinones (β-lactams) has occupied an important role in organic chemistry
and drugs. β-Lactam antibiotics are extensively applied to fight against microorganisms as antibiotic
drugs. The Staudinger's ketene-imine cycloaddition is one of the most common approaches in the synthesis
of 2-azetidinones. The aim of this paper to describe a methodology based on the use of 3-
(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4-(3H)-one (DEPBT) for the synthesis of 2-azetidinones
under mild reaction conditions at room temperature.
Methods: The present methodology deals with one pot [2+2] ketene-imine cycloaddition reaction of
imine and substituted ketene to synthesis of 2-azetidinones in mild condition at room temperature. In
addition, detailed experimental procedures are provided.
Results: A series of 2-azetidinones were synthesized in good to excellent yield via
one pot [2+2]
ketene-imine cycloaddition reactions. The obtained products were purified in good yield by simple
crystallization. All the synthesized compounds were well characterized by spectral and physical data.
Conclusion: A simple method for one-pot transformation of various carboxylic acids and imines to 2-
azetidinones using 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4-(3H)-one (DEPBT) has been developed.
The yield of [2+2] ketene-imine cycloaddition was good to excellent, and starting materials
were readily available. An aqueous work up and simple crystallisation was sufficient to obtain pure
products because DEPBT produces water-soluble by-products.