(Carbomethoxy)maleic Anhydride, a Highly Reactive New Dienophile and Comonomer

Article abstract of DOI:10.1021/jo00347a014

(Carbomethoxy)maleic anhydride (CMA), is an extremely reactive dienophile in <4+2> cycloadditions with butadiene, isoprene, and chloroprene.The second-order rate constants prove it to be more reactive than tetracyanoethylene.Diels-Alder reaction with anthracene gives the normal addition product.With cyclopentadiene, the endo adduct is obtained and with furan the exo adduct.With p-metoxystyrene, anethole, and diphenylethylene, the 2:1 Wagner-Jauregg-type adducts are obtained, while with styrene both Wagner-Jauregg and Diels-Alder ene adduct are formed.Copolymers form in certain conditions.With isobutyl and phenyl vinyl ether, an inverse-lectron-demand Diels-Alder reaction with CMA yields 2-isobutoxy- or 2-phenoxy-6-methoxy-3,4-dihydro-2H-pyran-3,4-dicarboxylic anhydride.These labile dihydropyrans revert to copolymers.