Electrosynthesis of Arylpyrroles and -indoles Under S<sub>RN</sub>1 Conditions
作者:M. Chahma、C. Combellas、A. Thiébault
DOI:10.1055/s-1994-25476
日期:——
Arylpyrroles and -indoles are electrosynthesized via a SRN1 type reaction. With pyrrolyl anion, the reaction leads mainly to α-substitution, but β-substitution and disubstitution are also observed. With indolyl anion, the main product corresponds to β-substitution. In both cases, the yield of the main product is higher than 50%.
S(RN)1 reactions can be performed with nitrogen carbanions as nucleophiles, and generally the reaction leads to a mixture of isomers. In the case of the pyrrolyl anion, position 2 is about four times more reactive than position 3. When the ortho positions of pyrrole are substituted by alkyl groups, the reactivity of position 2 increases while that of position 3 decreases. With tert-butyl groups as the substituents, no reaction at position 2 is observed. With the indolyl anion as the nucleophiIe, no substitution at position 2 or at the phenyl ring is observed, and only one product corresponding to monosubstitution at position 3 is obtained. Imidazolyl anions react preferentially at position 4 (5), and substitution of position 2 by a methyl group makes the coupling regioselective.
OHKURA, KAZUE;SEKI, KOH-ICHI;TERASHIMA, MASANAO;KANAOKA, YUICHI, HETEROCYCLES, 30,(1990) N, C. 957-962
New (pyrrolyl)-pyridinium and quinolinium salts have been prepared selectively in high yields by reacting (pyrrolyl)-pyridine or -quinoline and their derivatives with CF 3 SO 3 CH 3 in CH 2 Cl 2 . No methylation of the nitrogen of pyrrole was observed. Preliminary investigations revealed that these salts show a good response as nonlinear optics.