1,2,3-Oxadiazines and 1,2,3-Thiadiazines.
1,2,3-Oxadiazines and 1,2,3-thiadiazines are heterocycles with interesting biological applications. This chapter updates the previous work, concentrating on major new preparations, reactions, and concepts. The 1,2,3-oxadiazines 1 and their isomeric 4H- 2and 2H- 3 derivatives still remain elusive ring systems. However, analogs of the benzoxadiazine system 6 have been studied for their antimicrobial activities. The use of a derivative of the benzoxadiazine system 6 as the base for nucleotide analogs is also reported. The 1-oxide and 1,1-dioxides of 1,2,3-thiadiazines 7 and the 2H- and 4H-1,2,3-benzothiadiazine systems 8 are prepared by oxidation reactions. A cyclin-dependent kinase 4 (CDK4) inhibition study of a 1,1-dioxide derivative of benzothiadiazine system 8and the synthesis and carbonic anhydrase inhibition studies of thienothiadiazines and are also reported. Additionally, the antibacterial activity of a 1,1-dioxide derivative of benzothiadiazine system 8 has been studied.