Rearrangements Involving a Side-Chain CNO

Rearrangements Involving Cleavage of an O—N Bond 1. Rearrangements Involving a Side-Chain CNO 

As previously claimed (81AHC141), the general scheme of heterocylic rearrangements 1 2 presupposes a Z-shaped geometry of the side-chain 

By reacting with ammonia, the amidoxime 21 rearranges into 3,4-diami-nofurazan (22) (88CHE707). The same diaminofurazan 22 is also reached 

The literature (83JHC385) reports that nitrosation of benzisoxazoles 36 with isoamyl nitrite and sodium methoxyde results in a mixture of 37Z 

Our opinion is that the actual configuration of oximes 37 should be inverted. Nitrosation of 36 in the presence of an alcoholate should result in the two E and Z oximes the Z isomer will suffer a spontaneous base-induced rearrangement into the furazan 39 and will not be isolated. Furthermore, the reported spectroscopic data agree with the inverted configuration. The intermediacy of open-chain species in the rearrangement 

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