Curtius-like Rearrangement of an Iron–Nitrenoid Complex and Application in Biomimetic Synthesis of Bisindolylmethanes

A Curtius-like rearrangement of hydroxamates to isocyanates was discovered. This reaction was initiated from an iron­(II)–nitrenoid complex, which was generated by the iron­(II)-catalyzed cleavage of N–O bonds of functionalized hydroxamates. To demonstrate the efficiency of this new Curtius-like rearrangement in synthetic chemistry, a biomimetic strategy for the one-pot preparation of bisindolylmethanes was developed

Copper-Catalyzed Radical Cyclization To Access 3‑Hydroxypyrroloindoline: Biomimetic Synthesis of Protubonine A

An unprecedented copper-catalyzed intramolecular radical cyclization was developed for the synthesis of 3-hydroxypyrroloindoline skeletons in excellent yields. The 3-hydroxyl group was introduced by trapping the radical intermediate with molecular oxygen or TEMPO. This process represents a unique radical oxidation pathway for tryptamine/tryptophan derivatives and allows a rapid biomimetic synthesis of natural product protubonine A

Construction of Tetracyclic 3‑Spirooxindole through Cross-Dehydrogenation of Pyridinium: Applications in Facile Synthesis of (±)-Corynoxine and (±)-Corynoxine B

A facile and straightforward method was developed to construct the fused tetracyclic 3-spirooxindole skeleton, which exists widely in natural products. The formation of the tetracyclic 3-spirooxindole structure was achieved through a transition-metal-free intramolecular cross-dehydrogenative coupling of pyridinium, which were formed in situ by the condensation of 3-(2-bromoethyl)­indolin-2-one derivatives with 3-substituted pyridines. As examples of the application of this new methodology, two potentially medicinal natural products, (±)-corynoxine and (±)-corynoxine B, were efficiently synthesized in five scalable steps

Copper-Mediated Dimerization to Access 3a,3a′-Bis­pyrrolidino­indoline: Diastereoselective Synthesis of (+)-WIN 64821 and (−)-Ditrypto­phenaline

A copper-mediated cyclization and dimerization of tryptamine or tryptophan was developed to generate a <i>C</i>₂-symmetry C₃(sp³)–C₃(sp³) bridge with two contiguous stereogenic quaternary carbons in one step. Impressively, the ratio between exo and endo cyclization products varies when different protecting groups of Nb are utilized. This dimerization reaction could be conducted in gram scale. With this dimerization method, both endocyclo­tryptophan (+)-WIN 64821 and exocyclo­tryptophan (−)-ditrypto­phenaline were synthesized in 5 steps