Assembly of fully substituted triazolochromenes via a novel multicomponent reaction or mechanochemical synthesis

Abstract

A new metal-free one-pot three-component procedure towards fully substituted triazolochromenes has been developed, starting from commercially available materials. Salicylaldehydes and nitroalkenes were reacted under solvent-free conditions, followed by a 1,3-dipolar cycloaddition of the intermediate 3-nitro-2H-chromenes with organic azides in a one-pot two-step sequence. The triazolochromenes were formed with complete regioselectivity and new biologically relevant structures were synthesized via extension of the developed procedure and via postfunctionalization. The mechanochemical synthesis was carried out for several salicylaldehydes and gave a clear improvement in the yield of the corresponding triazolochromenes and consequently showed to be a viable alternative for solid salicylaldehydes.

Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues

“…Aldehyde building block 16 was a versatile starting material for further cyclization reactions. Synthesis of nitrochromenobenzofuropyridine 21 was achieved after treatment of 16 with nitrostyrene in the presence of DABCO applying our previously reported ball milling procedure [ 40 ]. The synthesis of 22 was performed using the Perkin reaction [ 41 ].…”

Microwave‐Assisted Iron(III)Chloride Catalyzed One‐Pot Michael Addition‐Cyclization for the Synthesis of 6H‐Chromeno[4’,3’:4,5] imidazo[1,2‐a]pyridine

“…[8a] Recently, chromene fused heterocyclic molecules have proven to be a fundamental structural building block in many pharmaceuticals. [9] Therefore, constant efforts have been made by many scientists to synthesize number of chromene-fused heterocyclic molecules, such as synthesis of tri-azolo chromene derivatives by Dehaen et al in 2018, [10] tetrahydrochromeno [4,3- Barkov et al in 2017, [11] benzo[d]chromeno [3',4' : 3,4]pyrrolo [2,1-b]thiazoloes by Yan et al in 2017, [12] furo [2,3-c]chromene derivatives by Yan et al in 2018, [13] benzopyrano [3,4-c]pyrrolidines by Korotaev et al in 2013, [14] chromeno indole derivatives by Speicher et al in 2013 [15] and so forth. The most notable examples of fused chromene includes natural products like Medicarpin(1), Lamellarin D (3) and 3-phenyl-3,4dihydrochromeno [4,3-c]pyrazole(4) showed various biological activities (Figure 1).…”

“…Therefore, constant efforts have been made by many scientists to synthesize number of chromene‐fused heterocyclic molecules, such as synthesis of tri‐azolo chromene derivatives by Dehaen et al . in 2018, [10] tetrahydrochromeno[4,3‐ c ]pyrazolo[1,2‐ a ]pyrazol‐11‐one by Barkov et al . in 2017, [11] benzo[ d ]chromeno[3’,4’ : 3,4]pyrrolo[2,1‐ b ]thiazoloes by Yan et al .…”

Efficient multicomponent synthesis of 2-aminopyridines catalysed by basic mesoporous materials

“…Multicomponent reactions (MCRs) have received considerable attention and are known as some of the most important reactions in organic and medicinal chem-istry [1][2][3][4][5][6][7][8][9][10][11]. One-pot multicomponent reactions are the useful path for the fac-ile synthesis of heterocycles with a biological value [12][13][14][15].…”