2H-1,3-Oxazines

The only known derivative of this class was prepared from ethyl 8-anilinecrotonate, ethyl acetoacetate, and benzaldehyde. In the first instance, a pyrimidine derivative is formed, this is then subjected to partial hydrolysis to form the 3,4-dihydro-l,3-2H-oxazine derivative (42). 

Imino derivatives of 4-oxo-3,4-dihydro-l,3-2H-oxazines (56) are hydrolyzed with dilute hydrochloric acid to the corresponding 2,4-... 

King and Durst have recently found the ring opening of trisubsti-tuted isoxazole quaternary salts to result in the formation of 1,3-(2H)-oxazine derivatives.1951... 

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