Synthetic and Theoretical Studies on the Reduction of Electron Withdrawing Group Conjugated Olefins Using the Hantzsch 1,4-Dihydropyridine Ester

Abstract

The Hantzsch 1,4-dihydropyridine ester (1) has been observed to be a useful selective reducing agent for the reduction of electron-withdrawing conjugated double bonds. The rate of this reaction was observed to be dependent upon the nature of the conjugated substituents and, consequently, the electronic nature of the unsaturated double bond. Theoretical calculations confirmed the importance of the HOMO-LUMO gap for this reaction and implicated a hydride transfer, agreeing with the experimentally observed reaction rate order. The calculations also revealed the importance of a boatlike structure of the 1,4-dihydropyridine nucleus as well as a trans arrangement of the ester groups to facilitate the hydride transfer.

Phosphoric Acid Catalyzed Enantioselective Transfer Hydrogenation of Imines: A Density Functional Theory Study of Reaction Mechanism and the Origins of Enantioselectivity

“…Garden et al proposed that in the reduction of electronpoor olefins the conformation of the ester groups of dihydropyridine 1 a is particularly important for hydride transfer, [32] in agreement with what was previously found for the conformation of the amide group in nicotinamide-mediated reductions. [33] To assess the magnitude of this effect in our case, starting from TS E1 , we located the transition states corresponding to the other relative cis/trans orientation of the ester groups (Scheme 5).…”

Electrochemical synthesis of 1,2,3,4,4,5,6-substituted 1,4-dihydropyridines

“…Numerous studies have been devoted to the study of the mechanism of oxidation of dihydropyridines of precisely this type. Proposals for the case in question include transfer of hydride ion [3], a one-electron oxidation with subsequent cleavage of a radical [4], and in the majority of cases a two-electron oxidation with cleavage of two protons [5][6][7].…”

C-Cyanation with 1-cyanobenzotriazole

“…1 H (300 MHz) and 13 C (75 MHz) NMR spectra were recorded on a 300 MHz NMR spectrometer in chloroform-d solution. Elemental and mass spectroscopy analyses were performed by the Analytical Laboratories, Dept.…”