Behaviour of Thiophenes Substituted with Electron-Withdrawing Groups in Cycloaddition Reactions

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

“…In contrast with the above mentioned behavior, when 2-nitrothiophene 3a was tested with 5, it gave traces of pyrrolyl-thiophene 13 formed by a heterocycloaddition followed by thermal rearrangement. (Della Rosa, et al, 2004). This unexpected behavior was also found with nitronaphthalenes as dienophiles.…”

“…(Figure 9) When methyl 5-nitrothiophene-3-carboxylate 29c was heated with less reactive isoprene, it gave pyrrolyl-thiophene 42 as the principal product formed (32%) by a hetero DA followed by thermal rearrangement ( Figure 9). (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).…”

“…(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.…”

Polar Diels-Alder Reactions Using Heterocycles as Electrophiles. Influence of Microwave Irradiation

“…Instead, the behavior of nitrobenzothiophenes is different. In its reaction with isoprene produce the hetero DA products but when react with 1-trimethylsilyloxy-1,3butadiene the corresponding dibenzothiophene were obtained as principal product [4,13].…”

“…Due to our interest in the cycloaddition chemistry of substituted aromatic heterocycles with electronwithdrawing groups, we have reported studies on the electrophilic character of aromatic compound with adequate substitution in their reactions with different dienes developed in benzene as the reaction medium and under conventional heating. These electrophiles react with dienes through polar Diels-Alder (P-DA) reactions to obtain in one step the respective cycloadducts aromatized [3][4][5][6][7][8][9][10][11][12][13][14]. Normally the reaction products are useful due to their biological activity [15][16][17].…”