Assembly of four modules onto a tetraazide platform by consecutive 1,2,3-triazole formations

Iterative click reactions using trivalent platforms for sequential molecular assembly

A facile synthesis of multi(triazole)s by iterative click reactions is disclosed. Good functional group tolerance of sequential click assembly by sulfur-fluoride exchange (SuFEx), copper-catalyzed azide-alkyne cycloaddition (CuAAC), and thia-Michael reaction realizes the iterative click reactions. Diverse multi(triazole)-type mid-molecules can be synthesized easily from readily available modules through good chemoselective reactions without functional group transformation steps.

Azido-type-selective triazole formation by iridium-catalyzed cycloaddition with thioalkynes

The iridium-catalyzed azide-thioalkyne cycloaddition was found to proceed much faster with benzyl azide than with phenyl azide. The high azido-type selectivity was also observed in other combinations of azides with different steric environments. This finding enabled the efficient assembly of three azidophilic molecules to triazido platforms by three sequential triazole-forming reactions.

New bis- and tetrakis-1,2,3-triazole derivatives: Synthesis, DNA cleavage, molecular docking, antimicrobial, antioxidant activity and acid dissociation constants

In this study, a series of bis- and tetrakis-1,2,3-triazole derivatives were synthesized using copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry in 73-95% yield. The bis- and tetrakis-1,2,3-triazoles exhibited significant DNA cleavage activity while the tetrakis-1,2,3-triazole analog 6g completely degraded the plasmid DNA. Molecular docking simulations suggest that compound 6g acts as minor groove binder of DNA by binding through several noncovalent interactions with base pairs. All bis- and tetrakis-1,2,3-triazole derivatives were screened for antibacterial activity against E. coli, B. cereus, S. aureus, P. aeruginosa, E. hirae, L. pneumophila subsp. pneumophila strains and antifungal activity against microfungus C. albicans and C. tropicalis strains. Compound 4d exhibited the best antibacterial activity among bis-1,2,3-triazoles against E. coli and E. hirae, while 6c exhibited the best antibacterial activity among tetrakis-1,2,3-triazoles against E. hirae. Furthermore, the best antifungal activity against C. albicans and C. tropicalis was reported for the compound 5, while 6d displayed the best antifungal activity against C. tropicalis and C. albicans. Reasonable iron chelating activities and DPPH radical scavenging abilities were found for some of the compounds. Finally, the acid dissociation constants (pK_a) of the bis-1,2,3-triazoles were also determined with the help of HYPERQUAD program using the data obtained from potentiometric titrations. The reported data here concludes that the bis- and tetrakis-1,2,3-triazoles are important cores that should be considered for further development of especially new anticancer agents acting through the DNA cleavage activity.

Modular synthesis of triazoles from 2-azidoacrylamides having a nucleophilic amino group

Assembling methods using 2-azidoacrylamides having a nucleophilic amino group are disclosed. Divergent transformations of the amine-type trivalent platform were accomplished with a wide variety of electrophiles to provide a broad...

Synthesis of Azidoanilines by the Buchwald-Hartwig Amination

We report a Buchwald-Hartwig amination compatible with azido functionality. Treatment of azidoaryl iodides and amines with fourth-generation Buchwald precatalyst coordinated by CPhos and sodium tert-butoxide in 1,4-dioxane at 50 °C afforded the corresponding azidoanilines while leaving the azido groups intact. The method showed a broad substrate scope and was applicable to the synthesis of diazido compounds as photoaffinity probe candidates of pharmaceutical amines and multiazido platform molecules.

Design, Synthesis, and Utility of Defined Molecular Scaffolds

A growing theme in chemistry is the joining of multiple organic molecular building blocks to create functional molecules. Diverse derivatizable structures—here termed “scaffolds” comprised of “hubs”—provide the foundation for systematic covalent organization of a rich variety of building blocks. This review encompasses 30 tri- or tetra-armed molecular hubs (e.g., triazine, lysine, arenes, dyes) that are used directly or in combination to give linear, cyclic, or branched scaffolds. Each scaffold is categorized by graph theory into one of 31 trees to express the molecular connectivity and overall architecture. Rational chemistry with exacting numbers of derivatizable sites is emphasized. The incorporation of water-solubilization motifs, robust or self-immolative linkers, enzymatically cleavable groups and functional appendages affords immense (and often late-stage) diversification of the scaffolds. Altogether, 107 target molecules are reviewed along with 19 syntheses to illustrate the distinctive chemistries for creating and derivatizing scaffolds. The review covers the history of the field up through 2020, briefly touching on statistically derivatized carriers employed in immunology as counterpoints to the rationally assembled and derivatized scaffolds here, although most citations are from the past two decades. The scaffolds are used widely in fields ranging from pure chemistry to artificial photosynthesis and biomedical sciences.

Nucleophilic transformations of azido-containing carbonyl compounds via protection of the azido group

Nucleophilic transformations of azido-containing carbonyl compounds are discussed. The phosphazide formation from azides and di(tert-butyl)(4-(dimethylamino)phenyl)phosphine (Amphos) enabled transformations of carbonyl groups with nucleophiles such as lithium aluminum hydride and organometallic reagents. The good stability of the phosphazide moiety allowed us to perform consecutive transformations of a diazide through triazole formation and the Grignard reaction.

Taming the reactivity of alkyl azides by intramolecular hydrogen bonding: site-selective conjugation of unhindered diazides

The intramolecular hydrogen bonding in the α-azido secondary acetamides (α-AzSAs) enabled site-selective integration onto the diazide modular hubs even without steric hindrance.