Convenient synthesis of tricyclic N(1)–C(2)-fused oxazino-indolones via [Au(i)] catalyzed hydrocarboxylation of allenes

Abstract

A new [Au(I)] catalyzed intramolecular hydrocarboxylation of allenes is presented as a valuable synthetic route to oxazino-indolones. The employment of 3,5-(CF3)2-C6H3-ImPyAuSbF6 as the optimal catalyst (5 mol%) was necessary to...

Fused Polycyclic NHC Ligands in Gold Catalysis: Recent Advances

“…Encouraged by these results and in collaboration with Ollevier, the authors applied this series of complexes in intramolecular Au(I)‐catalyzed hydrocarboxylation of allenes 29 for the synthesis of the tricyclic oxazino‐indolones 30 , a widespread scaffold in natural, biologically‐active and pharmaceutical compounds (Figure 11). [30] Taking into account that secondary hydrogen interactions between the carboxylic acid and a basic amino group, they extended the family to complexes 27 d and 27 e having respectively a 4‐dimethylaminophenyl and a 3‐dimethylaminophenyl group as lateral substituent. However, the electron‐rich aryl groups in 27 c – e induced a shielding of the electrophilic properties of the gold center and led to a decrease in catalytic activity, while the presence of electro‐deficient group in 27 b , inducing a destabilization of the intermediate catalytic species, allowed for an acceleration of the ring closure step.…”

“…Based on the promising results they obtained in the intramolecular Au(I)‐catalyzed hydrocarboxylation of allenes 29 for the synthesis of the tricyclic oxazino‐indolones 30 (Figure 11), Monari, Ollevier, and Bandini developed an unprecedented enantioselective variant of this transformation on the model substrate 41 (Figure 18). [30] They took advantage of the geometry of the ImPy platform to introduce chirality in the near‐metal environment by introducing an enantiomerically pure secondary alcohol function in the C5 position and developed catalysts 43 . Although the enantiomeric excesses in product 42 remained relatively moderate, this work represented the first enantioselective version of this transformation and showed promising opportunities for future developments by means of the high modularity of the ImPy platform.…”

Fluorinated Biphenyl Phosphine Ligands for Accelerated [Au(I)]-Catalysis

“…At the beginning of our investigation, we drew inspiration from our recent results involving CF 3 -containing imidazo­[1,5- a ]­pyridin-3-ylidene platforms (ImPys) for gold-catalyzed activation of allenes and alkynes . Building upon this, our focus shifted toward incorporating fluorine atoms and CF 3 groups onto the outer phenyl ring of the biphenyl core of JohnPhos-inspired A1 , 2 (Scheme ).…”