Research Projects

Bis(indole) alkaloids are important natural products due to their significant biological properties. Among them, axially chiral bis(indole) containing C4-indolyl indole scaffolds are unique due to their structural speciality and diverse bioactivities. Notably, the synthetic strategies to prepare such scaffolds are scarce. Moreover, the studies on their axial chiral versions are also limited due to their shorter half-lives. In this project, first a racemic synthetic strategy for the construction of arundanine-based alkaloids has been described. C4-selective direct aryl amination of indole scaffolds under transition metal catalysis using 2,1-benzisoxazoles (anthranilic) as a bifunctional agent is proposed as the key step. More importantly, the condensation of diazo acetate with aldehyde aryl amine substrate under Lewis acid can lead to the desired C4-indolyl indole scaffolds, a strategic platform for this class of alkaloids. Next, an asymmetric version to construct the axial chiral C4-indolyl indole scaffolds has also been proposed under the chiral oxazaborolidinium ion catalyst. Recently, hypervalent iodine reagents have been applied in large numbers of organic transformations due to its activity, stability and easy preparation. Further, in an alternative strategy for the construction of these scaffolds, we propose to develop a new type of indole-based hypervalent iodine reagent (indoleBX) where the iodine centre is attached to the indole’s N-center. After the development of such a hypervalent iodine reagent, it will be used for the direct installation of indole moiety at the C4 position of another indole scaffold via direct C-N bond formation which can further extend to the desired natural products via regular chemical transformations.