Studies On A Few Reactions Of Hantzsch Ester As A Organic Reducing Agent

In this thesis we explored the synthetic utility of Hantzsch 1,4-dihydropyridine(HEH) in several useful organic transformations. The thesis consists of two parts. In the first part, we present a brief introduction on the research progress recently made in the area concerning co-enzyme NADH model compound Hantzsch 1,4-dihydropyridine(HEH), focusing on its synthetic applications in reductive transformations, such as the selective reduction of theα,β-unsaturated carbonyl compounds and imines, and the reductive amination of carbonyl compounds, synthetic expanded the use on the basis of our previously investigation of its use and the mechanism. The second part deals with our own studies aimed at expanding the scopes of HEH as a biomimetic reducing agent in organic synthesis. We found that HEH/Pd/C was a very effective reagent combination for the selective reduction of aromatic azides and aromatic nitro compounds to the corresponding amines. The conditions were also used to effect the reduction of olefins with HEH, but the effectiveness of the reduction was found to depend largely on the structural features and substituents of the olefins. Substituted styrenes were reduced to the corresponding products in good to excellent yields, while the reduction of the isolated double bonds was not satisfactory. Finally, the possibility of employing HEH to achieve the synthesis of tetrahydropyran rings from dicarbonyl compounds, was tentatively explored.