A highly enantioselective synthetic route to hexahydropyrrolo[2,3-b]indoles via Lewis acid-catalyzed S2-type ring opening of activated aziridines with indoles having substitutions at 3- and other positions followed by cyclization in a domino fashion has been developed. Hexahydropyrrolo[2,3-b]indoles have been detosylated in the same pot to afford the corresponding products with free NH group in excellent yields (up to 95%) and enantioselectivity (up to >99%).

An efficient and green "on water" regio- and stereoselective synthetic route to chiral 1,2,4-oxadiazinanes and 1,4,2-dioxazinanes with excellent yields (up to 99%) and de/ee (>99%) has been developed for the first time via the domino ring-opening cyclization (DROC) of N-activated aziridines and epoxides with nitrones using LiClO/BuNBF a dual catalyst system. The developed green strategy features a broader substrate scope and mild reaction conditions, and successfully overcomes the competitive oxidative ring opening of aziridines. Further synthetic significances of this green protocol are the formation of the products (i) as single diastereomers starting from a mixture of cis/trans disubstituted aziridines via dynamic kinetic epimerization (DKE) and (ii) via a multicomponent approach starting from N-methyl hydroxylamine hydrochloride, benzaldehyde and aziridine.

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