Organocatalytic Atroposelective Synthesis of N−N Axially Chiral Indoles and Pyrroles by De Novo Ring Formation.

The first highly atroposelective construction of N−N axially chiral indole scaffolds was established via a new strategy of de novo ring formation. This strategy makes use of the organocatalytic asymmetric Paal–Knorr reaction of well‐designed N‐aminoindoles with 1,4‐diketones, thus affording N‐pyrrolylindoles in high yields and with excellent atroposelectivities (up to 98 % yield, 96 % ee). In addition, this strategy is applicable for the atroposelective synthesis of N−N axially chiral bispyrroles (up to 98 % yield, 97 % ee). More importantly, such N−N axially chiral heterocycles can be converted into chiral organocatalysts with applications in asymmetric catalysis, and some molecules display potent anticancer activity. This work not only provides a new strategy for the atroposelective synthesis of N−N axially chiral molecules but also offers new members of the N−N atropisomer family with promising applications in synthetic and medicinal chemistry. [ABSTRACT FROM AUTHOR]