Regiodivergent Metal-Controlled Synthesis of Multiply Substituted Quinolin-2-yl- and Quinolin-3-ylphosphonates

In this study, we developed a selective method for synthesis of multi-substituted quinoline-2-ylphosphonates and quinoline-3-ylphosphonates by copper- or gold-catalyzed reactions of phosphoryl-substituted conjugated ynones with 2'-amino-2,2,2-trifluoroacetophenones. The approach proposed makes it possible to obtain various substituted quinolines in good yields. It is also shown that (4,4,4-trifluoro-3-oxobut-1-yn-1-yl)phosphonate reacts with 2-aminoaryl ketones under non-catalytic conditions with formation of 4-substituted quinoline-2-ylphosphonates in high yields.

Friedlӓnder's synthesis of quinolines as a pivotal step in the development of bioactive heterocyclic derivatives in the current era of medicinal chemistry

In the current scenario of medicinal chemistry, quinoline plays a pivotal role in the design of new heterocyclic compounds with several pharmacological properties, so the search for new synthetic methodologies and their application in drug discovery has been widely studied. So far, many procedures have been performed for the preparation of quinoline scaffolds, among which Friedländer quinoline synthesis plays an important role in obtaining these heterocycles. The Friedländer reaction involves condensation between 2-aminobenzaldehydes and keto-compounds. The quinoline nucleus, once obtained through the Friedländer synthesis, has been extensively modified so that these derivatives can exhibit a large number of biological activities such as anticancer, antimalarial, antimicrobial, antifungal, antituberculosis, and antileishmanial properties. In this work, the focus is on the applicability of the Friedländer reaction in the synthesis of various types of bioactive heterocyclic quinoline compounds, which to date has not been reported in the context of medicinal chemistry. The main part of this review selectively focuses on research from 2010 to date and will present highlights of the Friedländer quinoline synthesis procedures and findings to address biological and pharmacological activities.

Access to 4-Trifluoromethyl Quinolines via Cu-Catalyzed Annulation Reaction of Ketone Oxime Acetates with ortho-Trifluoroacetyl Anilines under Redox-Neutral Conditions

An efficient Cu-catalyzed annulation reaction of ketone oxime acetates with ortho-trifluoroacetyl anilines has been disclosed. With the developed protocol, a series of 4-trifluoromethyl quinolines were obtained in good to excellent yields (58-99%) under redox-neutral conditions. The protocol also could be extended to ferrocene-based ketone oxime acetates for the construction of ferrocene-substituted fluorine-containing quinolines.

A NbO type Cu(ii) metal-organic framework showing efficient catalytic activity in the Friedländer and Henry reactions

A three-dimensional NbO type porous metal-organic framework 1 containing both tertiary amine groups and paddle wheel dinuclear Cu₂(COO)₄ secondary building units as the active centre was synthesized at room temperature. The activated framework 1' can be used as an efficient heterogeneous catalyst for the synthesis of quinoline derivatives by the Friedländer reaction and for the synthesis of β-nitroalcohols by the Henry (nitroaldol) reaction. This MOF-based heterogeneous catalyst is easily recycled and reused further without losing its structural integrity and catalytic activity.

Cerium(IV) ammonium nitrate is an excellent, general catalyst for the Friedländer and Friedländer-Borsche quinoline syntheses: very efficient access to the antitumor alkaloid luotonin A

The use of cerium(IV) ammonium nitrate as a catalyst of the Friedländer reaction allows the synthesis of polysubstituted quinoline derivatives in excellent yields, avoiding the traditional harshly basic or acidic conditions. Unlike most other previously known reagents, CAN allows double condensations and is also an excellent catalyst for the Borsche variation of the Friedländer reaction, which has been applied to the very efficient synthesis of the antitumor alkaloid luotonin A.