Doctoral Thesis / Dissertation from the year 2004 in the subject Chemistry - Organic Chemistry, Bangalore University / Central College (Department of Studies in Chemistry), language: English, abstract: The importance of ss-amino acids has been focused, particularly in the past few decades. They are found as components of many biologically active peptidic and nonpeptidic natural products with antibiotic, antifungal, cytotoxic, and other pharmacological properties. ss-Amino acids are produced in humans, animals, microorganisms, marine organisms, and plants either in free state or as part of a peptide or depsipeptide. The importance of nonpeptidic ss-amino acids has been nfocused particularly on the ss-lactam antibiotics, since naturally occurring penicillin derivatives have been discovered as broad antibiotic active agents. Over the years, a large number of these compounds have been prepared and tested, and a variety of new ss-lactam ring systems have been introduced such as cephems, cephalosporins, oxacephems, penems, carbapenems, oxapenams as well as monocyclic and polycyclic ring systems. ss-Amino acids have been known to play an important role in primary and secondary metabolism also. [...]