Intramolecular Hetero-Diels-Alder Reaction of Alkylidene- and Benzylidenepyrazolones and Benzylideneisoxazolones. Investigations toward the Conformation of the Transition State

Article abstract of DOI:10.1021/jo00239a024

Stereochemical aspects of the intramolecular hetero-Diels-Alder reaction of hetero dienes are studied.Knoevenagel condensation of aromatic aldehydes 1, 12, 15,, and 21 with pyrazolones 8a-h and isoxazolone 17 gave the corresponding hetero dienes, e.g.,9a-