On the reactivity of activated alkynes in copper and solvent-free Huisgen’s reaction

Alkynes as Privileged Synthons in Selected Organic Name Reactions

BACKGROUND

Alkynes are actually basic chemicals, serving as privileged synthons for planning new organic reactions for assemblage of a reactive motif, which easily undergoes a further desirable transformation. Name reactions, in organic chemistry are referred to those reactions which are well-recognized and reached to such status for being called as their explorers, discoverers or developers. Alkynes have been used in various name reactions. In this review, we try to underscore the applications of alkynes as privileged synthons in prevalent name reactions such as Huisgen 1,3-dipolar cycloaddtion via Click reaction, Sonogashira reaction, and Hetero Diels-Alder reaction.

OBJECTIVE

In this review, we try to underscore the applications of alkynes as privileged synthons in the formation of heterocycles, focused on the selected reactions of alkynes as a synthon or impending utilization in synthetic organic chemistry, which have reached such high status for being included in the list of name reactions in organic chemistry.

CONCLUSION

Alkynes (including acetylene) are an unsaturated hydrocarbon bearing one or more triple C-C bond. Remarkably, alkynes and their derivatives are frequently being used as molecular scaffolds for planning new organic reactions and installing reactive functional group for further reaction. It is worth mentioning that in general, the terminal alkynes are more useful and more frequently being used in the art of organic synthesis. Remarkably, alkynes have found different applications in pharmacology, nanotechnology, as well as being known as appropriate starting precursors for the total synthesis of natural products and biologically active complex compounds. They are predominantly applied in various name reactions such as Sonogashira, Glaser reaction, Friedel-crafts reaction, Castro-Stephens coupling, Huisgen 1.3-dipolar cycloaddtion reaction via Click reaction, Sonogashira reaction, hetero-Diels-Alder reaction. In this review, we tried to impress the readers by presenting selected name reactions, which use the alkynes as either stating materials or precursors. We disclosed the applications of alkynes as a privileged synthons in several popular reactions, which reached to such high status being classified as name reactions. They are thriving and well known and established name reactions in organic chemistry such as Regioselective, 1,3-dipolar Huisgen cycloaddtion reaction via Click reaction, Sonogashira reaction and Diels-Alder reaction.

A modular approach for multifunctional polymersomes with controlled adhesive properties

The bottom-up approach in synthetic biology involves the engineering of synthetic cells by designing biological and chemical building blocks, which can be combined in order to mimic cellular functions. The first step for mimicking a living cell is the design of an appropriate compartment featuring a multifunctional membrane. This is of particular interest since it allows for the selective attachment of different groups or molecules to the membrane. In this context, we report on a modular approach for polymeric vesicles, so-called polymersomes, with a multifunctional surface, namely hydroxyl, alkyne and acrylate groups. We demonstrate that the surface of the polymersome can be functionalized to facilitate imaging, via fluorescent dyes, or to improve the specific adhesion to surfaces by using a biotin functionalization. This generally applicable multifunctionality allows for the covalent integration of various molecules in the membrane of a synthetic cell.

Synthesis and cytotoxicity evaluation of aryl triazolic derivatives and their hydroxymethine homologues against B16 melanoma cell line

In this manuscript we describe synthesis and cytotoxicity evaluation of some triazolic derivatives against B16 melanoma cell line. For this purpose, we transformed a set of aromatic aldehydes into terminal alkynes, using Besthmann-Ohira reagent, and we made the corresponding hydroxymethyl homologated alkynes by an acetylene Grignard reagent. These generated two sets of alkynes were then subjected to a copper(I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC) using a solid-supported catalyst (Amberlyst A-21 CuI), with a third set composed of organic azides. Synthesized triazoles were then tested in vitro against B16 melanoma cell line. Amongst them, compounds a1b1 (R(1) = p-nitrophenyl, R(2) = benzyl), a4b1 (R(1) = naphthyl, R(2) = benzyl) and a4b5 (R(1) = naphthyl, R(2) = (R/S)- dioxolane) showed the best activity against B16 melanoma cells, with IC50 of 5.12, 3.89 and 6.60 μM respectively.

Synthesis of bi- and bis-1,2,3-triazoles by copper-catalyzed Huisgen cycloaddition: A family of valuable products by click chemistry

The Cu(I)-catalyzed azide-alkyne cycloaddition reaction, also known as click chemistry, has become a useful tool for the facile formation of 1,2,3-triazoles. Specifically, the utility of this reaction has been demonstrated by the synthesis of structurally diverse bi- and bis-1,2,3-triazoles. The present review focuses on the synthesis of such bi- and bistriazoles and the importance of using copper-promoted click chemistry (CuAAC) for such transformations. In addition, the application of bitriazoles and the related CuAAAC reaction in different fields, including medicinal chemistry, coordination chemistry, biochemistry, and supramolecular chemistry, have been highlighted.

Pressure-accelerated azide-alkyne cycloaddition: micro capillary versus autoclave reactor performance

Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel-process-window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide-alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide-alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high-pressure operation up to 1800 bar and a capillary flow reactor (up to 400 bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space-time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide-alkyne cycloadditions to widen the scope of the presented methodology.

Energetic polymeric networks prepared via a solvent- and catalyst-free thermal cycloaddition of azide-bearing polymers with alkynes and hydroxyl-isocyanate addition reactions

The construction of azide-bearing polymeric networks using a dipolarophile and a diisocyanate.

Synthesis and in vitro evaluation of potential anticancer activity of mono- and bis-1,2,3-triazole derivatives of bis-alkynes

In order to find new molecules with cytotoxic activity against cancer cells, we prepared bis-akyne amides derived from propiolic acid. The bis-alkynes were then transformed in their mono-1,2,3-triazole analogs onto the amide side, due to its greater reactivity, using a catalyst-free Huisgen's reaction. The mono-triazoles were then subjected to the copper (I)-catalyzed version of the previous reaction (CuAAC), using a supported catalyst, to produce bis-triazoles. All products were obtained pure after simple trituration or filtration procedures. All synthetic compounds were tested in vitro for their cytotoxic activity using B16 melanoma cells. Four compounds (7, 23, 25 and 33) showed activities in the micromolar range (<21 μM) whereas three compounds (3, 22 and 38) presented activity at low micromolar concentrations (<10 μM), and two analogs (2 and 13) were active at nanomolar levels (<1 μM).