Reactive Nitrogenous Molecules from Meldrum's Acid Derivatives, Pyrrole-2,3-diones, and Isoxazolones

Article abstract of DOI:10.1021/jo00189a025

Flash vacuum pyrolysis of 5-(aminomethylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (Meldrum's acid derivatives) 12 gives 4-hydroxyquinolines/4-quinolones 15 or 3-enaminoacroleins 22 in good to excellent yields.Intermediate (aminomethylene)ketenes and imidoylketenes are directly observed and their transformation into product 22 monitored by low-temperature IR spectroscopy.Imidoylketenes are also formed and observed upon thermal CO extrusion from pyrrole-2,3-diones 16.Isocyanoamines and fulminates are generated by pyrolysis of hydrazono- or oximino-Meldrum's acid derivatives 32 and 39, monitored by IR spectroscopy, and found to rearrange to cyanamides and cyanates, depending on substituents.The thermal reactions of isoxazol-5(4H)-ones and Meldrum's acid derivatives are compared and discussed.