Niobium Pentachloride Catalyzed Multicomponent Povarov Reaction

Abstract

A single-step method for the synthesis of furan-and pyranoquinoline derivatives through multicomponent Povarov reactions between aniline derivatives, benzaldehyde and two different enol ethers (2,3-dihydrofuran and 3,4-dihydropyran) using niobium pentachloride as catalyst under mild conditions, providing good yields and high diastereoselectivity, is described.

Diastereoselective Synthesis of Pyranoquinolines on Zirconium‐Containing UiO‐66 Metal‐Organic Frameworks

“…In this sense, the MOF can be considered as a “macroligand” of the Zr ions, which would explain the high diastereomeric selectivity observed. A similar mechanism has been proposed by da Silva et al to explain the diastereoselectivity of the NbCl 5 ‐catalyzed Povarov reaction, and steric hindrance has also been claimed to be the factor influencing the outcome of a reaction by controlling the orientation of its intermediates …”

“…There is still some controversy over the mechanism of the aza‐D–A reaction, as to whether it is a concerted or a stepwise reaction , , . It is generally accepted that the use of strong electrophilically activated azadienes and strong nucleophilically activated ethylenes favors a two‐step reaction.…”

Progress in the Chemistry of Tetrahydroquinolines

“…For instance, 25 mol% of GdCl 3 triggered the three-component reaction to deliver excellent yields of the corresponding THQs 516 and 517 with good diastereoselectivity (Scheme ). In addition, Sc­(OTf) 3 , BF 3 ·OEt 2 , NbCl 5 , , Sm­(OTf) 3 , ceric ammonium nitrate (CAN), CeCl 3 ·7H 2 O/NaI, and Al­(OTf) 3 were also employed as catalysts for the same reaction. This chemistry was applied to the synthesis of hexahydro 2 H -pyrano­[3,2- c ]­quinolines as selective σ 1 receptor ligands .…”

Synthesis of Quinoline Derivatives by Multicomponent Reaction Using Niobium Pentachloride as Lewis Acid

“…As part of our research work on synthetic methodologies using NbCl 5 in a variety of reactions [51][52][53][54][55][56][57][58][59][60], in this work, we described our studies in the multicomponent reactions between benzaldehyde, aniline derivatives, and phenylacetylene, for the synthesis of quinoline derivatives, in the presence of NbCl 5 .…”