Pd(II)‐Catalyzed, Bidentate Directing Group‐aided Alkylation of sp3 γ‐C−H Bonds: Access to 3‐Alkylated Thiophene/Furan and Benzothiophene/Benzofuran Motifs

Abstract

We report the Pd(II)‐catalyzed bidentate directing group 8‐aminoquinoline‐aided sp3 γ‐C−H alkylation of 3‐methyl‐ thiophene/furan‐2‐carboxylic acid and 3‐methyl‐ benzothiophene/benzofuran‐2‐carboxylic acid systems. While the 8‐aminoquinoline‐aided sp3 γ‐C−H functionalization including arylation or amidation or amination of carboxylic acid derivatives are well known, however, the Pd(II)‐catalyzed bidentate directing group 8‐aminoquinoline‐aided sp3 γ‐C−H alkylation is not explored. Notably, 2‐ and/or 3‐alkylated thiophene/furan and benzothiophene/benzofuran motifs are found in pharmaceutically active molecules. Accordingly, this work reveals the scope of the 8‐aminoquinoline‐aided sp3 γ‐C−H alkylation method, and its usefulness by enriching the libraries of 3‐alkylated thiophene/furan and benzothiophene/benzofuran motifs.