Hantzsch Ester
Diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate

Recent Literature

An efficient and highly enantioselective conjugate transfer hydrogenation of α,β-unsaturated ketones is catalyzed by a salt made from tert-butyl valinate and a recently introduced powerful chiral phosphoric acid catalyst (TRIP).
N. J. A. Martin, B. List, J. Am. Chem. Soc., 2006, 128, 13368-13369.

The use of a chiral imidazolidinone catalyst has provided a new organocatalytic strategy for the enantioselective reduction of β,β-substituted α,β-unsaturated aldehydes to generate β-stereogenic aldehydes using ethyl Hantzsch ester as the hydrogen source. In addition, an acceleration of E-Z isomerization prior to selective E-olefin reduction allows the use of geometrically impure enals in this operationally simple protocol.
S. G. Ouellet, J. B. Tuttle, D. W. C. MacMillan, J. Am. Chem. Soc., 2005, 7, 32-33.

A highly enantioselective hydrogenation of enamides is catalyzed by a dual chiral-achiral acid system. By employing a substoichiometric amount of a chiral phosphoric acid and acetic acid, low catalyst loadings of the chiral catalyst were sufficient to provide excellent yield and enantioselectivity of the reduction product.
G. Li, J. C. Antilla, Org. Lett., 2009, 11, 1075-1078.

α-Imino esters derived from aryl and alkyl keto esters could be reduced to the corresponding α-amino esters in excellent yields and in high enantiomeric excesses using 5 mol-% of a chiral phosphoric acid as catalyst, Hantzsch ester as hydride donor, and toluene as solvent.
G. Li, Y. Liang, J. C. Antilla, J. Am. Chem. Soc., 2007, 129, 5830-5831.

A thiourea-catalyzed transfer hydrogenation of various aromatic as well as aliphatic aldimines through hydrogen-bonding activation with Hantzsch 1,4-dihydropyridine as the hydrogen source gives the respective amines under acid- and metal-free reaction conditions.
Z. Zhang, P. R. Schreiner, Synlett, 2007, 1455-1457.

A biomimetic direct reductive amination of ketones relies on selective imine activation by hydrogen bond formation with thiourea as hydrogen bond donor and utilizes the Hantzsch ester for transfer hydrogenation. The method allows the efficient synthesis of structurally diverse amines.
D. Menche, J. Hassfeld, J. Li, G. Menche, A. Ritter, S. Rudolph, Org. Lett., 2006, 8, 741-744.

A hydrogen-bond-catalyzed, acid- and metal-free direct reductive amination of aldehydes uses thiourea as organocatalyst and the Hantzsch ester for transfer-hydrogenation. This methods allows for the high-yielding synthesis of diverse amines.
D. Menche, F. Arikan, Synlett, 2006, 841-844.

A chemoselective activation of a secondary amide with triflic anhydride in the presence of 2-fluoropyridine enables a mild reduction using triethylsilane, a cheap and rather inert reagent. Imines can be isolated after a basic workup or readily transformed to the aldehydes following an acidic workup. The amine moiety can be accessed by addition of Hantzsch ester to the reaction mixture.
G. Pelletier, W. S. Bechara, A. B. Charette, J. Am. Chem. Soc., 2010, 132, 12817-12819.

An achiral amine in combination with a catalytic amount of a chiral Brønsted acid can accomplish an aldol addition-dehydration-conjugate reduction-reductive amination with 2,6-diketones to provide cyclohexylamines as potential intermediates of pharmaceutically active compounds in good yields and excellent enantioselectivities.
J. Zhou, B. List, J. Am. Chem. Soc., 2007, 129, 7498-7499.

Consecutive hydroamination/asymmetric transfer hydrogenation under relay catalysis of an achiral gold complex/chiral Brønsted acid binary system allows a direct transformation of 2-(2-propynyl)aniline derivatives into tetrahydroquinolines with high enantiomeric purity.
Z.-Y. Han, H. Xiao, X.-H. Chen, L.-Z. Gong, J. Am. Chem. Soc., 2009, 131, 9182-9183.

A highly efficient and highly enantioselective Hantzsch ester mediated conjugate transfer hydrogenation of β,β-disubstituted nitroolefins is catalyzed by a Jacobsen-type thiourea catalyst.
N. J. A. Martin, L. Ozores, B. List, J. Am. Chem. Soc., 2007, 129, 8976-8977.

A highly efficient and enantioselective Hantzsch ester mediated conjugate reduction of β-nitroacrylates is catalyzed by a Jacobsen thiourea catalyst. The reaction is a key step in a new route to optically active β²-amino acids.
N. J. A. Martin, X. Chen, B. List, J. Am. Chem. Soc., 2008, 130, 13862-13863.

An operationally simple, tin-free reductive dehalogenation system allows the reduction of activated C-X bonds in good yields with excellent functional-group tolerance and chemoselectivity over aryl and vinyl C-X bonds in the presence of the well-known visible-light-activated photoredox catalyst Ru(bpy)₃Cl₂ in combination with iPr₂NEt and HCO₂H or Hantzsch ester as the hydrogen atom donor.
J. M. R. Narayanam, J. W. Tucker, C. R. J. Stephenson, J. Am. Chem. Soc., 2009, 131, 8756-8757.

A Brønsted acid catalyzed transfer hydrogenation of indole derivatives with Hantzsch dihydropyridine as the hydrogen source enables an efficient synthesis of various optically active indolines with high enantioselectivities.
M. Rueping, C. Brinkmann, A. P. Antonchick, I. Atoresei, Org. Lett., 2010, 12, 4604-4607.