The Divergent Synthesis of Nitrogen Heterocycles by Rhodium(I)-Catalyzed Intermolecular Cycloadditions of Vinyl Aziridines and Alkynes

Catalyst-controlled divergent intermolecular cycloadditions of vinylaziridines with alkynes have been developed. By using [Rh(NBD)₂]BF₄ as the catalyst, a [3 + 2] cycloaddition reaction was achieved with broad substrate scope and high stereoselectivity under mild reaction conditions. Moreover, the chirality of vinylaziridines can be completely transferred to the [3 + 2] cycloadducts. When the catalyst was changed to [Rh(η⁶-C₁₀H₈) (COD)]SbF₆, the alternative [5 + 2] cycloadducts were selectively formed under otherwise identical conditions.