A novel application of the Diels–Alder reaction: nitronaphthalenes as normal electron demand dienophiles

Ionic Liquids in Polar Diels-Alder Reactions Using Carbocycles and Heterocycles as Dienophiles

“…(Della Rosa, et al, 2004). We assumedacycloaddition of the diene to the heterodienophilic fragment of the nitro group forming the oxazine N-oxide (Paredes, et al, 2007;Della Rosa, et al, 2004). , According to the normal hetero DA mechanism, a second electron-withdrawing group placed on thiophene nucleus in 29c caused an increase in pyrrole yields.…”

“…In the case of 73, the low yields obtained could be explained by steric effects derived from the proximity of the nitro groups, which caused considerable overcrowding in the molecule. (Paredes, et al, 2007) Unexpected results were observed when using nitronaphthalenes with less reactive dienes such as 5 and 6. Interestingly, when 68 and 69 reacted with these dienes, they produced N-(1-naphthyl)-3-methylpyrrole 78 and N-(2-naphthyl)-3-methylpyrrole 79 with yields according to the electron-donor properties of the diene.…”

“…This effect is revealed by an increase in the yield of the DA reaction. (Paredes, et al, 2007; It has been demonstrated a good correlation between the difference in the global electrophilicity of the diene/dienophile interacting pair (Δω) and the feasibility of the cycloaddition.…”

“…In addition, we have been realized studies on the dienophilic character in DA reactions of other aromatic systems such as nitronaphthalenes. (Paredes, et al, 2007) In general, when these nitrodienophiles were exposed to a different dienes yielded the corresponding initial cycloadduct products, which normally suffer the thermal extrusion of the nitro group. Unexpected results were observed when using nitronaphthalenes with the less reactive dienes.…”

Experimental and theoretical studies on polar Diels–Alder reactions of 1-nitronaphathalene developed in ionic liquids

“…These electrophilic dienophiles were exposed to different dienes, strongly, moderately and poorly nucleophilic activated, under thermal conditions using molecular solvents as reaction media to achieve the corresponding hydroxyphenanthrene. 7 According to the nature of the substituent groups, this cycloaddition is considered a polar process. Thus, there are some interesting aspects related to the solvent dependence.…”