Tetrahydroquinoline is one of the most important simple nitrogen heterocycles, widely found in nature and in a variety of pharmacologically active compounds. Tetrahydroquinoline is an important structure for the synthesis of various biologically active derivatives.
Oxazines are heterocyclic compounds containing one oxygen and one nitrogen atom in a diunsaturated six-membered ring. The existence of isomers depends on the relative positions of the heteroatoms and the relative positions of the double bonds.