Applications of Hantzsch Esters in Organocatalytic Enantioselective Synthesis

Hantzsch esters (1,4-dihydropyridine dicarboxylates) have become, in this century, very versatile reagents for enantioselective organic transformations. They can act as hydride transfer agents to reduce, regioselectively, a variety of multiple bonds, e.g., C=C and C=N, under mild reaction conditions. They are excellent reagents for the dearomatization of heteroaromatic substances, and participate readily in cascade processes. In the last few years, they have also become useful reagents for photoredox reactions. They can participate as sacrificial electron and hydrogen donors and when 4-alkyl or 4-acyl-substituted, they can act as alkyl or acyl radical transfer agents. These last reactions may take place in the presence or absence of a photocatalyst. This review surveys the literature published in this area in the last five years.

Automated summary

Hantzsch esters have emerged as versatile reagents for enantioselective organic transformations in the last century. They can selectively reduce various multiple bonds, such as C=C and C=N, as hydride transfer agents under mild reaction conditions. Additionally, they are effective for the dearomatization of heteroaromatic substances and can participate in cascade processes. In recent years, they have also been employed in photoredox reactions, acting as sacrificial electron and hydrogen donors, as well as alkyl or acyl radical transfer agents.