Ring-opening and cyclization of aziridines with aryl azides: metal-free synthesis of 6-(triflyloxy)quinolines

Abstract

A metal-free synthesis of 6-(triflyloxy)quinolines has been developed via the ring-opening and cyclization of 2-aryl-1-tosylaziridines with 2-azidobenzaldehydes in the presence of TfOH.

2-Azidobenzaldehyde-Based [4+2] Annulation for the Synthesis of Quinoline Derivatives

“…The ring-opening of aziridines is a useful tool for the construction of N-heterocycles via cycloaddition or cyclization reactions [ 103 , 104 , 105 , 106 ]. Wan and co-workers utilized ring-opening and the cyclization of aziridines 45 for the synthesis of 3-substituted quinolines 46 ( Scheme 12 ) [ 107 ]. The TfOH-promoted denitrogenation of the azide group of 1 gave intermediate 47 and then 48 after deprotonation.…”

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

“…When considering general methods for the quinoline core formation, aromatic ortho-substituted carbonyl compounds attract attention as decent and easily available reagents. While the ortho-amino carbonyl reagents are not always easily accessible and sometimes unstable (e.g., aminoaldehydes), both o-azidoaldehydes [58][59][60][61][62][63][64][65] and o-azidoketones [66][67][68][69] have been proved to be appropriate substrates for quinoline derivatives synthesis. Recently, the method for the synthesis of 3-acylsubstituted quinolines from o-azidobenzaldehydes and 1,3dicarbonyl compounds was reported [70,71] (Figure 2a).…”

A predictive chemistry DFT study of N2O functionalization for the preparation of triazolopyridine and triazoloquinoline scaffolds

“…[42][43][44][45][46][47] The reaction was performed in two steps, the first consisting of the lithiation of 2-alkylpyridine and 2-alkylquinoline derivatives, and the second one involving nitrous oxide for its functionalization to triazolopyridine and triazoloquinoline scaffolds (see Scheme 1), to be compared with other synthesis strategies like those with t BuONO 48 or azides. 49 The reaction pathway was hypothesized (see Scheme 2) as an initial nucleophilic attack of the carbanion on nitrous oxide to yield a diazotate, followed by the elimination of LiOH to generate the diazo species and finally cyclization to give the final desired product.…”

“…42–47 The reaction was performed in two steps, the first consisting of the lithiation of 2-alkylpyridine and 2-alkylquinoline derivatives, and the second one involving nitrous oxide for its functionalization to triazolopyridine and triazoloquinoline scaffolds (see Scheme 1), to be compared with other synthesis strategies like those with t BuONO 48 or azides. 49…”