Microwave-assisted synthesis of indole- and azaindole-derivatives in water via cycloisomerization of 2-alkynylanilines and alkynylpyridinamines promoted by amines or catalytic amounts of neutral or basic salts

Two-pot synthesis and photophysical studies of 1,6-disubstituted 5-aza-indoles from succinaldehyde and N-aryl propargylic-imines

A two-pot synthesis of 5-aza-indoles has been developed from aqueous succinaldehyde and N-aryl propargylic-imines. This overall protocol involves: (i) the metal-free [3 + 2] annulation of aqueous succinaldehyde and N-aryl propargylic-imines to access 2-alkynyl-pyrrole-3-aldehydes and (ii) Ag-catalyzed 6-endo-dig-cyclization to obtain substituted 5-aza-indoles in the second pot. The 5-aza-indoles showed engaging photophysical activities, and the practicality of this pot-economic gram-scale synthesis has been demonstrated.

Synthesis of Medicinally Important Indole Derivatives: A Review

Indoles constitute a widely occurring functional group in nature and are present in an extensive number of bioactive natural products and medicinally important compounds. As a result, exponential increases in the development of novel methods for the formation of indole core along with site-specific indoles have been established. Conventional methods for the synthesis of indoles are getting replaced with green methods involving ionic liquids, water as a solvent, solid acid catalyst, microwave irradiation and the use of nanoparticles under solvent-free conditions. In addition, there are immense applications of the substituted indoles in diverse fields.

Click Nucleophilic Conjugate Additions to Activated Alkynes: Exploring Thiol-yne, Amino-yne, and Hydroxyl-yne Reactions from (Bio)Organic to Polymer Chemistry

The 1,4-conjugate addition reaction between activated alkynes or acetylenic Michael acceptors and nucleophiles (i.e., the nucleophilic Michael reaction) is a historically useful organic transformation. Despite its general utility, the efficiency and outcomes can vary widely and are often closely dependent upon specific reaction conditions. Nevertheless, with improvements in reaction design, including catalyst development and an expansion of the substrate scope to feature more electrophilic alkynes, many examples now present with features that are congruent with Click chemistry. Although several nucleophilic species can participate in these conjugate additions, ubiquitous nucleophiles such as thiols, amines, and alcohols are commonly employed and, consequently, among the most well developed. For many years, these conjugate additions were largely relegated to organic chemistry, but in the last few decades their use has expanded into other spheres such as bioorganic chemistry and polymer chemistry. Within these fields, they have been particularly useful for bioconjugation reactions and step-growth polymerizations, respectively, due to their excellent efficiency, orthogonality, and ambient reactivity. The reaction is expected to feature in increasingly divergent application settings as it continues to emerge as a Click reaction.

Access to benzo-fused aza[7]helicene via unexpected indolization of alkyne-amine

An efficient base-mediated indolization of alkyne-amine for the synthesis of quinolone-fused indole was developed and further applied to synthesize di- and triaza[7]helicenes bearing two and three pentagons, respectively.

Benefits and applications of microwave-assisted synthesis of nitrogen containing heterocycles in medicinal chemistry

Nitrogen containing heterocycles are of immense research interest because they are often found as naturally occurring bioactive compounds.

Synthesis of indoles from alkynes and a nitrogen source under metal-free conditions

This review deals with the methodologies published in the last ten years, which used metal-free conditions to prepare indoles starting from alkynes and nitrogen compounds.

Microwave-assisted synthesis of 7-azaindoles via iron-catalyzed cyclization of an o-haloaromatic amine with terminal alkynes

An efficient and practical procedure was developed to prepare 7-azaindole, starting from an o-haloaromatic amine and corresponding terminal alkynes under microwave irradiation and the scope was demonstrated with a number of examples. The valuable features of this procedure included the iron-catalyzed cyclization, short reaction times and convenient operation. Furthermore, iron catalysis is an interesting alternative to homogeneous catalysis for the synthesis of heterocycles.

An efficient and practical procedure was developed to prepare 7-azaindole, starting from an o-haloaromatic amine and corresponding terminal alkynes under microwave irradiation and the scope was demonstrated with a number of examples.

Optimizing ligand structure for low-loading and fast catalysis for alkynyl-alcohol and -amine cyclization

The catalytic performance was evaluated for a series of [Ru(Cp/Cp*)(P^R₂N^R′₂)(MeCN)]PF₆ complexes, in which the steric and electronic properties of the primary coordination sphere were varied (R = Ph, t-Bu, Bn; and Cp vs. Cp*).

Facile synthesis of heavily-substituted alkynylpyridines via a Sonogashira approach

A robust synthesis of highly-substituted alkynylpyridines via a Sonogashira approach is described, providing a library of functionalized pyridines for biological studies.

Green synthesis of α-aminophosphonate derivatives on a solid supported TiO2 -SiO2 catalyst and their anticancer activity

Syntheses of a new series of biologically potent α-aminophosphonates were accomplished by one-pot Kabachnik-Fields reaction using TiO2-SiO2 as solid supported catalyst under microwave irradiation conditions. The chemical structures of all the newly synthesized compounds were confirmed by analytical and spectral (IR, 1H, 13C, 31P NMR, and mass) data. Their anticancer nature was evaluated by screening the in vitro activity on two human cancer cell lines, HeLa and SK-BR-3. Compounds 4i and 4o showed the best activity on these cancer cells even though the majority of the compounds, and particularly 4l and 4p, have good cytotoxic activity against them.