The aza-Claisen rearrangement product of the Michael adducts 2 from \alpha-dialkylaminoacetophenone oximes and DMAD underwent fragmentation to give dialkylaminomaleate, and benzonitrile at reflux in acetonitrile. The fragmentation was assumed to proceed through an unstable 4H-1,2-oxazete 6. The same reaction performed at room temperature, in addition to the nitrile and maleate, gave the corresponding 2-(2-dialkylamino-1-phenylethylideneaminooxy)-but-2- enedioic acid dimethyl esters 8 and 9. Compounds 9 isomerized to 8 on heating in acetonitrile.
COŞKUN, NECDET and ARIKAN, NEVİN (2003) "Search for a Nonelectrocyclic Cyclization of Nitrosostyrene: Rearrangements of Michael Adducts from DMAD and \alpha-Dialkylamino Oximes," Turkish Journal of Chemistry: Vol. 27: No. 1, Article 3. Available at: https://journals.tubitak.gov.tr/chem/vol27/iss1/3