Beilstein J. Org. Chem.2022,18, 796–808, doi:10.3762/bjoc.18.80
dienophiles in refluxing toluene afforded diverse spirotetrahydrocarbazoles. This reaction is an important development of the Levyreaction by using 2-methylindole to replace ethyl indole-2-acetate and successfully provides facile access to important polysubstituted spiro[carbazole-3,3'-indolines], spiro
[carbazole-2,3'-indolines], spiro[carbazole-3,5'-pyrimidines] and spiro[carbazole-3,1'-cycloalkanes] in satisfactory yields and with high diastereoselectivity.
Keywords: Diels–Alder reaction; indole; indolo-2,3-quinodimethane; Levyreaction; tetrahydrocarbazole; spirooxindole; Introduction
(reaction 2 in Scheme 1) [75][76][77]. It was noticed that only ethyl indole-2-acetate was successfully employed as the precursor to generate the active indolo-2,3-quinodimethane intermediate in the Levyreaction, which greatly limited its practical synthetic value. We envisioned that other substituted
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Graphical Abstract
Scheme 1:
Construction of diverse tetrahydrocarbazoles via Levy-type reaction.