Benzamidoximes, formation

It must be pointed out that the "amide process allows the preparation of oxadiazole containing acylable group in the substituent. For example, 3-phenyl-5-hydroxy methyl oxadiazole has been obtained in 55% yields from benzamidoxime formate and glycolamide. 

The first A/ -oxides of the 1,2,4-thiadiazole ring system have been reported and were prepared by condensation of benzamidoximes (86) with 4,5-dichloro-l,2,3-dithiazohum chloride (87). A -labelling showed the compounds to be 4-oxides (88) and a mechanism was proposed for their formation. Alkyl amidoximes and arylamidoximes with electron-withdrawing substituents did not give A/ -oxides, but only the dithiazolone (89) and the dithiazolthione (90) <96CC1273>. 

If benzamidine is replaced by benzamidoxime, then the 4-oxide derivative 107 is obtained as a minor product (8%) together with 4-chloro-l,2,3-dithiazol-5-one 108 (32%) and the 5-thione 109 (15%) (Equation 30). The formation of the 4-oxide, as opposed to the isomeric 2-oxide, was confirmed by mass spectral and 15N NMR data. The yield of the 4-oxide product could be improved by using an O-acyl benzamidoxime in place of benzamidoxime <1999J(P1)2243>. 

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