Azetidin-2-ones, Synthon for Biologically Important Compounds†

Azetidin-2-one, a four-membered cyclic lactam (β-lactam) skeleton has been recognised as a useful building block for the synthesis of a large number of organic molecules by exploiting the strain energy associated with it, in addition to its use in the synthesis of a variety of β-lactam antibiotics. Efforts have been made in exploring such new aspects of β-lactam chemistry using enantiomerically pure β-lactams as versatile intermediates for the synthesis of aromatic β-amino acids and their derivatives, peptides, polyamines, polyamino alcohols, amino sugars and polyamino ethers. The development of methodologies based on β- lactam nucleus is now referred as 'the β-lactam synthon methods'. The selective bond cleavage of the strained ring coupled with further interesting transformation render this fascinating molecule as a powerful building block. This provides an access to diverse structural type of synthetic target molecules lacking β-lactam ring structure. This review provides an account of synthesis of organic compounds having biological significance at the same time lacking β-lactam ring, by using β-lactam as synthon.