A C–H Activation Approach to the Tricyclic Core of Glionitrin A and B

Synthesis of diketopiperazines
has been of long-standing interest
in both natural product synthesis and medicinal chemistry. Here, we
present an operationally convenient and efficient approach to the fused indoline-diketopiperazine
tricyclic core of glionitrin A/B and related structures using a Pd-catalyzed
C–H activation reaction to form the indoline five-membered
ring. Exploratory work aimed at elaborating the tricyclic structures
into the corresponding natural products is discussed.