One-Pot Synthesis of Functionalized 2,3-Disubstituted Indolines via K2CO3-Promoted Cascade Michael/Aza-Cyclization Reactions

Diastereoselective synthesis of trans-2,3-dihydroindoles via formal [4 + 1] annulation reactions of a sulfonium ylide

We have established an in situ generated sulfonium-ylide mediated annulation to construct 2,3-disubstituted-2,3-dihydroindoles. The [4 + 1] annulation approach relied on Michael addition/substitution reactions. These reactions were carried out at ambient temperature to deliver dihydroindoles with excellent yields and diastereoselectivities. Moreover, the versatility of this approach allows for the introduction of various functional groups, enabling further diversification of the dihydroindoles. Also, the cascade approach was broadened to synthesize dihydrobenzofurans.

Ethyl 2-[2-(4-Nitrobenzoyl)-1H-indol-3-yl]acetate

Ethyl 2-[2-(4-nitrobenzoyl)-1H-indol-3-yl]acetate was prepared in good yield and characterized by the aza-alkylation/intramolecular Michael cascade reaction of (E)-ethyl 3-[2-(tosylamino)phenyl]acrylate with 2-bromo-4′′-nitroacetophenone, followed by desulfonative dehydrogenation with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) The structure of the newly synthesized compound was determined using 1H-,13C-NMR, IR and mass spectral data.

Asymmetric synthesis of 2,3-disubstituted indolines via an organocatalytic intramolecular Michael addition

An asymmetric synthesis of 2,3-disubstituted indolines has been developed via an organocatalytic intramolecular Michael addition.