Synthesis of highly substituted tetrahydroquinolines using ethyl cyanoacetate via aza-Michael–Michael addition

Abstract

A three-component cascade reaction involving 2-alkenyl aniline, aldehydes, and ethyl cyanoacetate in the presence of DBU to synthesize highly substituted 1,2,3,4-tetrahydroquinolines is reported.

Enantioselective Chromatographic Separation and Lipase Catalyzed Asymmetric Resolution of Biologically Important Chiral Amines

“…It represents a crucial intermediate of fine chemical industry such as medicine, agrochemicals, and dyes [21,23]. It is beneficial for the production of esters, amides, acids, and nitriles and is used as an intermediate for the synthesis of 3-cyanopiperidin-2,6-diones [24], substituted tetrahydroquinolines [25] 2-amino-4,6dimethoxypyrimidine an intermediate for sulfonylurea herbicides, and the insecticide flufenitrile [26]. Based on their biological and synthetic impact, many asymmetric strategies have been adopted for the preparation of chiral amines in the enantiopure form [2,8].…”

“…As a polyfunctional synthon with both electrophilic (C-3, C-1) and nucleophilic (N, C-2) reactive sites (Figure 2) [21], cyanoacetamides have been customized to prepare diverse heterocyclic moieties [21,22,27,28] with different ring sizes (Figure 2), such as azirine [29], pyrrole [30], thiophene [31,32], pyrazole [33], isothiazole [34], imidazole [35], thiazole [36], thiadiazole [37], pyridine [38], pyridinone [39], pyrane [40], pyridazine [41], pyrimidine [28], thiazine [42], and triazine [36]. As a polyfunctional synthon with both electrophilic (C-3, C-1) and nucleophilic (N, C-2) reactive sites (Figure 2) [21], cyanoacetamides have been customized to prepare diverse heterocyclic moieties [21,22,27,28] with different ring sizes (Figure 2), such as azirine [29], pyrrole [30], thiophene [31,32], pyrazole [33], isothiazole [34], imidazole [35], thiazole [36], thiadiazole [37], pyridine [38], pyridinone [39], pyrane [40], pyridazine [4...…”