Batcho-Leimgruber indole synthesis
The Batcho-Leimgruber-Indole-Synthesis or Leimguber-Batcho-Reaction is a name reaction of organic chemistry . It is the synthesis of indole from ortho- nitrotoluene and takes place in two steps.
The reaction was named after the Hoffmann-La-Roche chemists Andrew D. Batcho and Willy Leimgruber, who first reported on it in 1971.
Overview reaction
In the first step, a condensation reaction occurs between the ortho- nitrotoluene 1 and the dimethylformamide dimethylacetal 2 . In the second step, the ring closure follows and indole 3 is obtained as the product .
Reaction mechanism
The following reaction mechanism is described in the literature.
At the beginning, the ortho- nitrotoluene is deprotonated by the triethylenediamine 4 . In the next step, the lone pair of electrons on the carbanion attacks the electrophilic carbon atom of dimethylformamide-dimethylacetal 5 . Subsequent electron rearrangements lead to the elimination of methanol and triethylenediamine and intermediate stage 6 is obtained. Another methanol molecule is split off and an enamine 7 is formed. In this case, the oxygen bound to the nitrogen is substituted with hydrogen. Raney nickel is used as the catalyst . This is followed by ring closure and proton rearrangement, so that molecule 8 is obtained. By splitting off dimethylamine and isomerization in the last step, indole 9 is obtained.
Individual evidence
- ^ A b Zerong Wang: Comprehensive Organic Name Reactions and Reagents , Wiley, 2010, ISBN 9780470638859 , pp. 258-262, doi: 10.1002 / 9780470638859 .
- ↑ Jie Jack Li: Name Reactions: A Collection of Detailed Mechanisms and Synthetic Applications , 5th Edition, Springer Science & Business Media, 2014, ISBN 9783319039794 , p. 35 in the Google book search.
- ^ Tōhoku Daigaku: Third International Congress of Heterocyclic Chemistry , Tohoku University, 1971, p. 462.