Preface [Hot Topic: β-Lactams: Synthesis, Stereochemistry, Synthons and Biological Evaluation (Guest Editor: Bimal K. Banik)]

The importance of the stereodivergent synthesis of chiral and achiral β-lactams is ever increasing in connection with the structure-activity relationship study and the development of new derivatives of the β-lactam antibiotics and inhibitors of β- lactamases. Due to the increased bacterial resistance, there has been effort expended to prepare new structural types having the 2-azetidinone ring as a common feature. The synthesis of a wide variety of heterocyclic compounds using β-lactams as synthons becomes the most remarkable target in β-lactam research. The vitality and diversity of this issue are reflected in the wide range of significant topics addressed by six prominent active groups in this area and by the fact that they are from different countries. Each one of the six articles presented in this issue has focused on the recent aspects in the β-lactam research. Examples included are synthesis of β-lactam rings using various methods, asymmetric synthesis, stereoselectivity of these reactions, use of these molecules for the synthesis of several biologically active compounds and development of β-lactamase inhibitors. Chmielewski and his group describe a powerful strategy for the preparation of oxygen analogs of penicillins and cephalosporins. A wide and general asymmetric synthesis of β-lactams and their use in natural and non-natural products has been described by Palomo and his group. Burnett describes the development of β-lactams as entirely new unique cholesterol absorption inhibitors. Deshmukh's and Alcaide's group demonstrate the great potential of β-lactams as synthons for the synthesis of biologically active compounds. Development of modified penicillin-and cephalosporin-derived β-lactamase inhibitors along with their mechanism of action has been provided by Buynak. He has also provided the color figure on the cover page of this issue. I take this opportunity to sincerely thank and congratulate the authors for their excellent and timely contribution. These reviews will surely provide a deeper understanding of the art of β-lactam research to the chemists at industrial and / or academic research institutions throughout the world.