A straightforward and versatile approach to the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles from alkyl halides via a one-pot, three-component reaction

Recent Progress in Catalytic Synthesis of 1,2,3-Triazoles

1,2,3-triazoles represent a functional heterocyclic core that has been at the center of modern organic chemistry since the beginning of click chemistry. Being a versatile framework, such an aromatic ring can be observed in uncountable molecules useful in medicine and photochemistry, just to name a few. This review summarizes the progress achieved in their synthesis from 2015 to today, with particular emphasis on the development of new catalytic and eco-compatible approaches. In doing so, we subdivided the report based on their degree of functionalization and, for each subparagraph, we outlined the role of the catalyst employed.

Organocatalyzed preparation of 1,4,5-trisubstituted-glycosyl-1,2,3-triazole derivatives

Organocatalytic coupling of glycosyl azides with enolates of active ketones and esters through azide-enolate [3 + 2] cycloaddition in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) furnished 1,4,5-trisubstituted-glycosyl-1,2,3-triazole derivatives in excellent yield. The reaction condition is simple and can be scaled-up. Graphical abstract Coupling of glycosyl azides with active ketones through azide-enolate [3 + 2] cycloaddition in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) furnished 1,4,5-trisubstituted-glycosyl-1,2,3-triazole derivatives in excellent yield.

Flow Hydrodediazoniation of Aromatic Heterocycles

Continuous flow processing was applied for the rapid replacement of an aromatic amino group with a hydride. The approach was applied to a range of aromatic heterocycles, confirming the wide scope and substituent-tolerance of the processes. Flow equipment was utilized and the process optimised to overcome the problematically-unstable intermediates that have restricted yields in previous studies relying on batch procedures. Various common organic solvents were investigated as potential hydride sources. The approach has allowed key structures, such as amino-pyrazoles and aminopyridines, to be deaminated in good yield using a purely organic-soluble system.

Antifungal activity of 1'-homo-N-1,2,3-triazol-bicyclic carbonucleosides: A novel type of compound afforded by azide-enolate (3+2) cycloaddition

The first report of 1'-homo-N-1,2,3-triazol-bicyclic carbonucleosides (7a and 7b) is described herein. Azide-enolate (3+2) cycloaddition afforded the synthesis of this novel type of compound. Antifungal activity was evaluated in vitro against four filamentous fungi (Aspergillus fumigatus, Trichosporon cutaneum, Rhizopus oryzae and Mucor hiemalis) as well as nine species of Candida spp. as yeast specimens. These pre-clinical studies suggest that compounds 7a and 7b are promising candidates for complementary biological studies due to their good activity against Candida spp.

A straightforward and versatile protocol for the direct conversion of benzylic azides to ketones and aldehydes

We report that the benzyl azido group is directly converted to carbonyls in good yields through a rapid hydrolysis (basic conditions) of benzylideneamides generated readily/efficiently in situ under a very simple procedure involving conventional reagents.