94144-99-7Relevant articles and documents
Dihydropyrans from 1,4-cycloaddition of enamines to arylmethylenepyrazolones. Polar character of the thermal rearrangement of the resulting cycloadducts
Abdel-Rahman,Abdel-Ghany
, p. 1281 - 1291 (2007/10/02)
The inverse electron demand hetero-Diels-Alder reaction of arylmethylenepyrazolones with enamines results in the selective formation of 3,4-dihydro-2H-pyran derivatives. These cycloadducts under thermodynamic conditions, are transformed via the zwitterion, which can be captured in the presence of tetracyanoethylene (TCE), as the more stable Michael-type adducts. The zwitterion could also be the intermediate for the cyclic adducts.