Synthesis of N-unsubstituted 1,2,3-triazoles via a cascade including propargyl azides, allenyl azides, and triazafulvenes

Abstract

About thirty NH-1,2,3-triazoles with at least one additional functional group in a side chain at C-4 were prepared from propargyl substrates. These reactions included propargyl azides and their [3,3]-sigmatropic rearrangement to generate short-lived allenyl azides, which cyclized to form triazafulvenes that could be trapped by addition of N-or O-nucleophiles. In most cases, simple substrates and cheap sodium azide were utilized as starting compounds, and the syntheses were performed by using a one-pot procedure without isolation of any dangerous azides. This method to prepare NH-1,2,3-triazoles turned out to be compatible with quite different substitution patterns of the propargyl substrate.

Glucosyl‐1,2,3‐triazoles derived from eugenol and analogues: Synthesis, anti‐Candida activity, and molecular modeling studies in CYP‐51

“…The deacetylated 1,2,3‐triazoles ( 23 – 28 ) were obtained with yields in the range of 30–98% after methanolysis of glucosides 17 – 22 (Safavi et al, 2019). In order to evaluate the importance of the saccharide unit in the structure of the compounds, the respective non‐glycosylated triazoles ( 29 – 34 ) were also synthesized from the reaction of the alkynes 7 – 12 with sodium azide and acetic acid, thus obtaining yields in the range of 57–61% (Banert et al, 2016).…”

Allylic azides: synthesis, reactivity, and the Winstein rearrangement

“…The rearrangement of propargyl azides was originally reported by Banert and has since been termed the Banert cascade (Scheme 45a). 4,161,[233][234][235][236][237][238] Much like the Winstein rearrangement, the Banert cascade starts with a [3,3]-sigmatropic rearrangement. This is followed by a 6-π electrocyclization and a nucleophilic trap to generate NH-1,2,3-triazoles.…”

Divergent Mechanisms of the Banert Cascade with Propargyl Azides

“…One potentially efficient 1 H -triazole synthesis is via the Banert cascade (Figure and Scheme ). , The Banert cascade has been used for this purpose in several synthetic contexts. − …”