Quinoxaline Chemistry: Developments 1963-1975

Publisher This chapter aims to survey developments in the field of quinoxaline chemistry. Quinoxalines are comparatively easy to prepare. It is noted that Quinoxaline N-oxides are well-recognized. Their reactions and their pharmacological actions continue to stimulate many investigations. Certain unusual quinoxaline derivatives such as 1,3-ethano-1,2,3,4-tetrahydroquinoxaline (2)7 are prepared together with many condensed quinoxalines. Antibiotics of the triostin and quinomycin series isolated from cultures of Streptomyces aureus, as shown by the degradative study, contain a quinoxaline-2-carboxylic acid residue. The recent 13C nuclear magnetic resonance (NMR) and mass spectrometric study of quinomycin A has led to revised structures for the quinomycins, which are originally thought to be cross-linked with a dithian rather than a thioacetal unit. The chapter essentially describes the synthesis, physical properties, derivatives, and general reactions of quinoxalines. In specific, various methods for the synthesis of quinoxalines include preparation of quinoxalines from o-Diamines, preparation of quinoxalines by intramolecular cyclization reactions, and from alloxazines and diazepines. Physical properties discussed in the chapter include ionization properties, ultraviolet absorption spectra, and nuclear magnetic resonance spectra.