Synthesis and Anti-Tumor Activity Evaluation of Novel 7-Fluoro-4-(1- Piperazinyl) Quinolines

Vilsmeier-Haack Cyclisation as a Facile Synthetic Route to Thieno [2,3- b] Quinolines (Part I)

Abstract:

Quinoline ring system is extensively dispensed in natural products, especially in alkaloids. Moreover, thieno[2,3-b]quinolines have vast biological activities, including urea transporter inhibition, anti-microbial, antitumor, antioxidant, anti-inflammatory, and antiproliferative EGFR tyrosine kinase inhibition. Vilsmeier-Haack is considered the most facile and promising set of synthetic routes, leading to 2-chloro-3-formylquinolines through Vilsmeier-Haack cyclisation of N- arylacetamides, which are subsequently used as key intermediates for the synthesis of thieno[2,3-b]quinolones (Tqs). Many varieties of thieno[2,3-b]quinolines (Tqs) ring systems, specifically concerning medicinal chemistry, have been developed over the past decade. In light of these facts, this review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of thieno[2,3-b]quinolines through the Vilsmeier-Haack reaction. In this study, the methods of preparation and the chemical reactivity of (Tqs) by using the Vilsmeier-Haack reaction are discussed. Since the beginning of the 21st century, they have been advancing towards synthesizing substituted Tqs. It can be concluded that substituted Tqs can be used as building blocks for the synthesis of polyfunctionalized heterocyclic compounds with pharmacological interest.

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

The acceptorless dehydrogenative coupling (ADC) reaction is an efficient method for synthesizing quinoline and its derivatives. In this paper, various substituted quinolines were synthesized from 2-aminobenzyl alcohols and aryl/heteroaryl/alkyl secondary alcohols in one pot via a cyclometalated iridium-catalyzed ADC reaction. This method has some advantages, such as easy availability of raw materials, mild reaction conditions, wide range of substrates, and environmental friendliness which conforms to the principles of green chemistry. Furthermore, a gram-scale experiment with low catalyst loading offers the potential to access the aryl/heteroaryl quinolones in suitable amounts. In addition, the antibacterial and antifungal activities of the synthesized quinolines were evaluated in vitro, and the experimental results showed that the antibacterial activities of compounds 3ab, 3ad, and 3ah against Gram-positive bacteria and compound 3ck against C. albicans were better than the reference drug norfloxacin.

Synthesis and reactivity of thieno[2,3‐b]quinoline derivatives (Part II)

As a continuation of our previous review entitled “Vilsmeier‐Haack cyclisation as a facile synthetic route to thieno[2,3‐b]quinolines (Part I).” This review describes the methods of preparation and the chemical reactivity of thieno[2,3‐b]quinolines, which might show interesting biological activities.

4-Aminoquinolines Bearing a 1,3-Benzodioxole Moiety: Synthesis and Biological Evaluation as Potential Antifungal Agents

In search of new environmentally friendly and effective antifungal agents, a series of 4-aminoquinolines bearing a 1,3-benzodioxole moiety were prepared and their structures were fully elucidated by spectroscopic analyses. The antifungal activities of all the target compounds against five phytopathogenic fungi were evaluated in vitro. The results revealed that most of the newly synthesized compounds exhibited obvious inhibitory activities at the concentration of 50 μg/mL. Among them, 6-(furan-2-yl)-N-(4-methylphenyl)-2H-[1,3]dioxolo[4,5-g]quinolin-8-amine hydrochloride (7m) displayed more promising antifungal potency with EC₅₀ values of 10.3 and 14.0 μg/mL against C. lunata and A. alternate, respectively. Particularly, the EC₅₀ value of 7m against C. lunata was 7.3-fold as potent as the standard azoxystrobin. There were some significant morphological alterations in the mycelia of C. lunata when treated with 7m at 50 μg/mL. Additionally, the preliminary structure-activity relationships (SARs) were also discussed. Thus, this study suggests that 4-aminoquinolines bearing a 1,3-benzodioxole moiety are interesting scaffolds for the development of novel antifungal agents.