A One-Pot Cascade Strategy toward Organocatalytic Enantioselective Construction of Fused Benzimidazoles

Herein, we describe an asymmetric assembly of ortho-aromatic diamines and formyl tethered Michael acceptors forming chiral fused benzimidazoles. A cinchona-alkaloid-derived bifunctional squaramide catalyst enables the methodology through on-site dihydrobenzimidazole formation followed by an aza-Michael addition/oxidation cascade. This protocol stands out for its excellent catalytic efficiency over the background reaction and its mild conditions, making it more practical. Various Michael acceptors, including enones, ester, and thioester, were successful substrates in this study. Additionally, this methodology has demonstrated scalability and successfully showcased postsynthetic transformations.