Multi-component Reaction Synthesis Of Triazine And Thiazide Compounds

The continuing interest in the chemistry of 1,3-oxazines or 1,3-thiazines, manifested by numerous papers and patents, is partially attributable to the biological activity of some 1,3-oxazines or 1,3-thiazines and to the discovery of antibiotics containing the 1,3-oxazine or 1,3-thiazine ring. What's more important, 1,3-oxazines or 1,3-thiazines also function as useful synthetic intermediates. Therefore, we investigated the cycloaddtion of N-acyl imines with various alkenes or alkynes, affording 1,3-oxazines or 1,3-thiazines. The results are showed as follows:(1) We have developed two new multicomponent reactions and discussed the reaction mechanism of these processes;the first one constitutes a facile synthesis of 2-amino-5,6-dihydro-4H-1,3-thiazin-3-ium chloride salts or 2-amino-5,6-dihydro-4H-1,3-oxazin-3-ium chloride salts through N-acyl imine or N-thioacyl imine [4+2] cycloaddtion with aromatic alkenes, and the second reaction is not the same [4+2] cycloaddtion but a Biginelli-like three-component process leading to hexahydro-4-phenyl-1H-pyrano[2,3-d]pyrimidin-2(8aH)-ones or hexahydro-4-phenyl-1H-pyrano[2,3-d]pyrimidine-2(8aH)-thiones.(2) A novel three-component reaction yielding 2-amino-4H- 1,3-oxazines or 2-amino-4H- 1,3-thiazines in a one-pot procedure has been developed. This approach allows for considerable flexibility in the nature of both the alkyne R~1 group and the aldehyde R~2 group, facilitating the preparation of a diverse array of 2-amino-4H-1,3-oxazines and 2-amino-4H-1,3-thiazines. We have also discussed the reaction mechanism of this multi-component raction.(3) In this thesis, vourious synthetic methods of these compounds were reviewed, especially the method of N-acyl imine or N-thioacyl imine [4+2] cycloaddtion.