The reactivity of the pyrrole ring in nucleophilic aromatic substitution has been evaluated for the first time by rate measurements for the piperidinodenitration of 1-methyl-2,5-dinitropyrrole (1) at varying temperatures. Relative rates (krel) have been established at 25°C and show that 1 is markedly less reactive than 2,5-dinitrofuran and 2,5-dinitrothiophene, the krel values being 1, 2.4 × 106, and 4.4 × 103, respectively. A less significant difference is found with the rate of 1,4-dinitrobenzene (krel = 9.6). The factors affecting the observed reactivities and activation parameters are discussed.
Nucleophilic Substitution at the Pyrrole Ring. Comparison with Furan, Thiophene, and Benzene rings in Piperidinodenitration / Giancarlo, Doddi; Gabriello, Illuminati; Mencarelli, Paolo; Franco, Stegel. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 41:17(1976), pp. 2824-2826. [10.1021/jo00879a008]
Nucleophilic Substitution at the Pyrrole Ring. Comparison with Furan, Thiophene, and Benzene rings in Piperidinodenitration
MENCARELLI, Paolo;
1976
Abstract
The reactivity of the pyrrole ring in nucleophilic aromatic substitution has been evaluated for the first time by rate measurements for the piperidinodenitration of 1-methyl-2,5-dinitropyrrole (1) at varying temperatures. Relative rates (krel) have been established at 25°C and show that 1 is markedly less reactive than 2,5-dinitrofuran and 2,5-dinitrothiophene, the krel values being 1, 2.4 × 106, and 4.4 × 103, respectively. A less significant difference is found with the rate of 1,4-dinitrobenzene (krel = 9.6). The factors affecting the observed reactivities and activation parameters are discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
