Hantzsch ester

Technical Specifications

Product Description & Scientific Applications

Hantzsch ester (diethyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate; HEH) is a 1,4-dihydropyridine dicarboxylate and a synthetic analogue of the reduced nicotinamide cofactor NADH. Like the cofactor, it is a mild organic hydride donor: under mild conditions it transfers hydrogen to reduce C=C, C=N and activated C=O bonds.

Reduction of imines and reductive amination. With a chiral phosphoric acid catalyst, Hantzsch ester reduces preformed ketimines to enantioenriched amines; the same catalysis reduces the imine formed in situ from a ketone and an arylamine, so the chiral amine is obtained directly by reductive amination, cleanly across a range of ketone structures.

Synthesis of α-amino esters. With a chiral phosphoric acid, it reduces α-imino esters derived from aryl and alkyl keto esters to the corresponding enantioenriched α-amino esters.

Conjugate reduction of enals. Paired with a chiral imidazolidinone catalyst that activates the substrate through iminium-ion formation, it transfers hydrogen to β,β-disubstituted α,β-unsaturated aldehydes to give β-stereogenic saturated aldehydes. The catalyst isomerises the double bond ahead of reduction, so mixtures of E- and Z-enal converge on the same enantiomer, and the delivery tolerates groups that are themselves prone to reduction such as aldehydes and halides.

Reduction of α-ketoesters. With chiral copper(II)–bisoxazoline complexes acting as alcohol-dehydrogenase mimics, it reduces α-ketoesters to the corresponding α-hydroxy esters.

Dearomatising reduction of quinolines. Under chiral Brønsted-acid catalysis, Hantzsch ester drives a cascade transfer hydrogenation of quinolines, adding hydrogen across the heterocyclic ring to give 2-aryl- and 2-alkyl-substituted 1,2,3,4-tetrahydroquinolines, a route applied in alkaloid synthesis.

Photoredox electron donor. Under violet light (390 nm), Hantzsch ester acts as an organic electron donor and photoreductant: it forms electron donor–acceptor complexes with suitable acceptors and undergoes single-electron transfer, generating carbon radicals from carboxylic-acid-derived precursors and reducing the metal catalyst — nickel(II) to catalytically active nickel(0) — so that decarboxylative cross-couplings run without a separate photocatalyst.

Shipping Destinations

• EU & UK: Priority delivery, 2–5 business days.
• United States (DDP): 3–7 business days, duties and taxes prepaid.
• EFTA Countries (DDP): 3–7 business days, duties and taxes prepaid.
• Worldwide: 7–14 business days, selected locations.