Gold‐ and silver‐catalyzed novel intramolecular cycloisomerizations of nitrogen or carbon‐tethered indolylcyclopropenes to furnish biologically and pharmaceutically valuable azepino‐[4,5‐b]indole and spiro[indoline‐3,4′‐piperidine] derivatives have been developed. Both reactions exhibit high chemoselectivity and stereospecificity through completely different reaction pathways. Based on mechanistic studies, it is well demonstrated that gold and silver catalysts act differently to promote the anti‐ and syn‐addition and the steric effect of the catalysts play an important role to switch the addition mode, affording the catalyst‐controlled‐divergent synthesis.

Recent developments on Pd complex-catalyzed asymmetric additions in the last five years have been presented in this context. As can be seen from this paper, lots of Pd complex-catalyzed asymmetric reactions have been reported in last five years. The Pd-catalyzed asymmetric additions of CLX bonds (X = C, O, N) with various nucleophiles including boronic acids are very efficient and highly stereoselective under mild conditions. These type reactions have been developed into well-established methods for the stereoselective construction of carbon-carbon and carbon-heteroatom bonds in organic synthesis.

Homogeneous gold catalysts are interesting as they can act as potent carbophilic Lewis acids to activate the π bonds of alkynes, allenes, and alkenes. Many impressive applications for the formation of C−C or C−heteroatom bonds have been found due to the excellent functional group compatibility of these catalysts and the air and moisture tolerance of their reactions. Here, we have developed gold‐catalyzed novel intramolecular cycloisomerizations of nitrogen or oxygen‐tethered cyclopropenes with propargylic esters. The reaction proceeded through different pathways according to different substituent styles, affording 5‐azaspiro[2.5]oct‐7‐enes and bicyclo[4.1.0]heptanes.

Novel intramolecular cycloisomerizations of nitrogen-tethered cyclopropenes with indole in the presence of Brønsted acids have been developed. The reactions proceeded through the same pathway but stopped at different stages according to different substituent styles, affording azocino[5,4-b]indole 2 and (epiminoethano)cyclopenta[b]indole 4 in moderate to good yields.

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