New cycloaddition reactions of 1-phenyl-4-vinylpyrazole
作者:Mercedes Medio Simón、José Sepúlveda Arques
DOI:10.1016/s0040-4020(01)82108-6
日期:1986.1
products (4) and (8), and also the 1:2 adducts (5), (6) and (9) resulting from an “ene” reaction of the initially forced cycloadducts. The obtention of the adducts (5) and (6) in equimolecular amounts is a good example of the non-regioselective character of the “ene” reaction. The reaction with tetracyanoethylene takes place through the olefinic substituent giving the π2 + π2 adduct (10).
Diels-Alder cycloaddition of vinylpyrazoles. Synergy between microwave irradiation and solvent-free conditions
作者:Angel Díaz-Ortiz、JoséR Carrillo、Enrique Díez-Barra、Antonio de la Hoz、María J Gómez-Escalonilla、Andrés Moreno、Fernando Langa
DOI:10.1016/0040-4020(96)00473-5
日期:1996.7
When subjected to microwave irradiation and solvent-free conditions vinylpyrazoles undergo Diels-Alder cycloadditions within 6–30 min to give acceptable yields of easily purified products. This methodology overcomes the most important disadvantages of the classical conditions and it permits the reaction to be extended to low reactive dienophiles, such as ethyl phenylpropiolate, not described by classical