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This study describes a new rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes using a Cu(OAc)2 oxidant for building a spirocyclic ring system, which includes the functionalization of an aryl C(sp2)H bond and addition/protonolysis of an alkene CC bond. This method is applicable to a wide range of 5-aryl-2,3-dihydro-1H-pyrroles and internal alkynes, and results in the assembly of the spiro[indene-1,2′-pyrrolidine] architectures in good yields with excellent regioselectivities. [ABSTRACT FROM AUTHOR]

A practical method for the synthesis of azepine derivatives, a typical seven-membered heterocyclic ring system, was developed and involves the use of hexafluoroantimonic acid to catalyze a formal [3+2+2] cycloaddition of aziridines with two alkynes. This method was applicable to two of the same or different terminal alkynes for the [3+2+2] cycloaddition with unactivated aziridines, and furnished the corresponding azepine derivatives in good yields with good levels of chemo- and regioselectivity. The mechanism was also discussed according to the results of the in situ HRMS and 1H NMR analysis. [ABSTRACT FROM AUTHOR]

Silber schmiedet den Ring: Eine Silber ‐ katalysierte [5+2] ‐ Cycloaddition zur Synthese von Azepin ‐ Derivaten wurde entwickelt. In nur einer Stufe werden vier neue Bindungen zwischen einem γ ‐ Aminoketon und einem Alkin aufgebaut. Diese Methode stellt somit eine neue Hetero ‐ [5+2] ‐ Cycloaddition zur Synthese von Heptacyclen dar. [ABSTRACT FROM AUTHOR]