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Indole 2,5-diketopiperazines (DKPs) are an important type of metabolic cyclic dipeptides containing a tryptophan (Trp) unit possessing a range of interesting biological activities. The intriguing structural features and divergent activities have stimulated tremendous efforts towards their efficient synthesis. Herein, we report the development of a unified strategy for the synthesis of three Trp-containing DKPs, namely tryprostatin A, and maremycins A and B, via a sequential C-H activation strategy. The key Trp skeletons were synthesized from the inexpensive, readily available alanine via a Pd(ii)-catalyzed β-methyl C(sp 3 )-H monoarylation. A subsequent C2-selective prenylation of the resulting 6-OMe-Trp by Pd/norbornene-promoted C-H activation led to the total synthesis of tryprostatin A in 12 linear steps from alanine with 25% overall yield. Meanwhile, total syntheses of maremycins A and B were successfully accomplished using a sequential Pd-catalyzed methylene C(sp 3 )-H methylation as the key step in 15 linear steps from alanine., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Rh(iii)-catalyzed cascade C-H activation/annulation/lactonization of quinoline-4-ols and alkynes has been reported. A broad range of tetracyclic pyrano[2,3,4-de]quinolines have been prepared in one-step with good functional group tolerance, excellent site selectivity, and high efficiency.

Pd-Catalyzed sequential monoarylation/amidation of C(sp 3 )-H bonds of alanine enabled by a removable 5-methoxyquinolin-8-amine (MQ) auxiliary is described. This process is highly efficient and compatible with a variety of functional groups, providing a general and practical access to various α-amino-β-lactams. The synthetic potential of this protocol is further demonstrated by the stereoselective synthesis of orthogonally protected anti-α,β-diamino acids.

A Pd(II)-catalyzed arylation of methylene C(sp(3))-H bonds in aliphatic amides directed by our newly developed PIP directing group with aryl iodides/bromides has been achieved. Arylation occurs efficiently with a broad range of aryl halides and amides.