Kinetics and mechanism of N-substitution of indoles and carbazoles in Vilsmeier–Haack acetylation
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 10,p. 1284-1287
- https://doi.org/10.1039/p29770001284
Abstract
The rate constants of acetylation of several pyrroles, indoles, and carbazoles by the Vilsmeier–Haack reagent (NN-dimethylacetamide–carbonyl chloride) have been measured in 1.2-dichloroethane at 25 °C. Most substrates undergo N-substitution and the data strongly support a mechanism involving rate determining direct attack on the nitrogen atom. The order of susceptibility to the electrophile for positions 1–3 of the indole nucleus is C-3 > N-1 > C-2. Differences in behaviour towards N-substitution of pyrrole, indole, and carbazole are discussed in terms of loss of resonance energy in the transition states.Keywords
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