A General Synthesis of 3,5-Dihalo-2H-1,4-oxazin-2-ones from Cyanohydrins
In a novel approach starting from O-trimethylsilyl protected or unprotected cyanohydrins and oxalyl chloride or bromide, a series of unknown 6-substituted 3,5-dihalo-2H-1,4-oxazin-2-ones were prepared.The method was shown to be efficient for various types of cyanohydrins; however cyclization was not obtained with cyanohydrins containing bulky substituents, electron-rich aryl or heteroaryl groups.A mechanism is proposed.
Meerpoel, Lieven,Hoornaert, Georges
p. 905 - 908
(2007/10/02)
SYNTHESIS OF 3,5-DIHALOGENO-2H-1,4-OXAZIN-2-ONES FROM CYANOHYDRINES
The title compounds 4 were obtained on treatment of cyanohydrines 3 of aliphatic and aryl aldehydes with oxalyl chloride or bromide in chlorobenzene at 90 deg C.Evidence for their structure is given by their spectroscopic data and by the Diels Alder reaction of 4a and 4g with acetylenic dienophiles to yield substituted pyridines.Cycloaddition was also observed with ethene.
Meerpoel, L.,Hoornaert, G.
p. 3183 - 3186
(2007/10/02)
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