In Tandem Enantioselective Intramolecular Heck‐Matsuda Reactions directly from Anilines
Tomaz Henrique Duarte Chorro, Edson Leonardo Scarpa de Souza, Otto Daolio Köster, Ellen Christine Polo, Rafaela C. Carmona, Vitor H. Menezes da Silva, João M. Batista, Carlos Roque D. Correia
Abstract
Abstract A new enantioselective intramolecular strategy for the synthesis of enantioenriched bridged benzoxacines, unsaturated spirobenzofurans, 2,3‐dihydrobenzofuran and 2,3‐indoline acetate scaffolds in a tandem‐like diazotization/Heck‐Matsuda process directly from anilines has been developed. The process combines the in situ diazotization of the aniline, followed by the intramolecular Heck‐Matsuda reaction, thus skipping the isolation and purification of potentially unstable or hard‐to‐synthesize aryldiazonium salts. The practicality and robustness of the sequence were demonstrated by the synthesis of 30 complex motifs in yields up to 91% and enantiomeric ratios up to 97:3, including quaternary stereocenters. The in‐tandem processes from anilines were compared to conventional Heck‐Matsuda reactions using pre‐synthesized aryldiazonium salts. With few exceptions, the reactions starting directly from the anilines afforded better overall yields and enantioselectivity, demonstrating the efficiency of the method. magnified image