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A concise and facile approach for the construction of 2-hydroxy-2-substituted indol-3-ones was developed through an oxidative cyclization of 2-aminophenyl-1,3-dione. Using CAN and TEMPO as oxidants, C2-quaternary 2-hydroxy-indolin-3-ones were efficiently installed in moderate to excellent yields (up to 99%). Moreover, this developed protocol was further applied to synthetic studies towards natural product matemone by starting from readily available 2-amino-4-bromobenzoic acid, and the precursor for matemone was efficiently installed.

An intramolecular [3 + 2]-annulation of amide-linked donor-acceptor cyclopropane with in situ-generated imine is described. As a result, diverse hexahydropyrrolo[3,2-c]quinolinones, as the tricyclic core of martinellines, were efficiently assembled in good to excellent yield (up to 93%) with a good diastereomeric ratio (up to 98:2).

With the aid of the hydrogen-bond relay of (S)-camphorsulfonic acid, the enantioselective exo-Diels–Alder cycloaddition of cyclic enones and 2-vinyl-1H-indoles catalyzed by prolinosulfonamide was developed. The corresponding Diels–Alder cycloadducts were readily obtained by a single recrystallization, free of column chromatography. Consequently, tetracyclic tetrahydrocarbazole ring systems with three contiguous stereogenic centers were prepared in moderate yields with excellent diastereoselectivities (exo/endo up to >20:1) and enantioselectivities (up to > 99 % ee).

The enantioselective DAR of cyclic enones with 2-vinylindoles is achieved with the aid of hydrogen-bond relay from (S)-camphorsulfonic acid.

A series of novel 2,3- or 2,5-dispirooxindole-piperazine ring systems were efficiently constructed through the acid-promoted self-1,3-dipolar [3+3] cyclizations of azomethine ylides derived from isatin with various primary or cyclic secondary amines. Interestingly, the regioselectivity of this self-[3+3] cyclization could be effectively tuned by varying the structural features of substrates. The unprecedented 2,5-dispirooxindole-piperazine skeleton was achieved in good diastereoselectivity by employing 1,2,3,4-tetrahydroisoquinoline, while using pyrrolidine or glycine methyl ester furnished the 2,3-dispirooxindole-piperazine scaffold in excellent diastereoselectivity (only a single isomer formed).

A series of novel 2,3- or 2,5-dispirooxindole-piperazine ring systems were efficiently constructed through the acid-promoted self-1,3-dipolar [3+3] cyclizations of azomethine ylides derived from isatin with various primary or cyclic secondary amines. Interestingly, the regioselectivity of this self-[3+3] cyclization could be effectively tuned by varying the structural features of substrates. The unprecedented 2,5-dispirooxindole-piperazine skeleton was achieved in good diastereoselectivity by employing 1,2,3,4-tetrahydroisoquinoline, while using pyrrolidine or glycine methyl ester furnished the 2,3-dispirooxindole-piperazine scaffold in excellent diastereoselectivity (only a single isomer formed).