New Route for the Synthesis of Hetaryl‐1,5‐benzodiazepines: Part 2

New coumarin chalcones 3j–p were conveniently obtained in high yields via Claisen-Schmidt condensation reaction, when acetyl coumarin 1 reacted with 3-aryl-1-phenyl pyrazole-4-carbaldehydes 2j–p in boiling ethanol in the presence of triethyl amine as a catalyst. Also, two synthetic pathways were afforded for the synthesis of novel tetrazolo[1,5-a]pyrimidinyl-2H-chromen-2-ones 5a-p. The first pathway is a multistep process including formation and separation of chalcones, which then were allowed to react with 5-aminotetrazole 4. While, the second pathway is a highly efficient one-pot three-component condensation reaction of 3-acetyl coumarin 1, aromatic aldehydes 2a-p and 5-aminotetrazole 4 under green and mild reaction conditions by using acetic acid (AcOH) as a catalyst and solvent. The molecular structure of products was established on the basis of their NMRs, IR and elemental analysis data. Solvent optimization was carried out in the reaction producing 3-(5-Phenyl-4,5-dihydrotetrazolo[1,5-a]pyrimidin-7-yl)-2H-chromen-2-one (5a). The advantages to using environmental-friendly acetic acid are simple operation, short reaction time, high efficient (97%), operationally facile and wide tolerance of starting materials. objective: The advantages of using environmental-friendly AcOH are simple operation, short reaction time, high efficient (97%), operationally facile and wide tolerance of starting materials.

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Synthesis and Chemistry of 1,2,4,3-Triazaphosphole Derivatives

Ali

Hassanin

Assiri

et al. 2023

COC

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This review describes the progress made during the last fifty years in the synthesis and chemistry of 1,2,4,3-triazaphospholes. This class of compounds has attracted tremendous homogeneous catalysis and interest in molecular materials science. These fascinating phosphorus heterocycles have conjugated π systems with high degrees of aromaticity. 1,2,4,3-Triazaphospholes can be designed through [3+2] cyclocondensation between functionalized hydrazines with phosphonoimidates that allow the incorporation of additional donor substituents into specific positions of the phosphorus heterocycle. In addition, [4+1] cyclocondensation between functionalized amidrazones and active phosphorus reagents is the most synthetically accessible method. The used strategies facilitated synthetic access to a completely new set of triazaphospholes leading to a much broader scope for potential applications. 1,2,4,3-triazaphospholes displayed reactivity towards a variety of reagents. The phosphorus is particularly prone to undergo oxidative 1,1-addition. Protic reagents such as alcohols, phenols, and amines can be added across the P=N bond of 2H-1,2,4,3-triazaphospholes to yield the dihydro-1,2,4,3-triazaphosphole derivatives. 1H- and 2H-1,2,4,3-triazaphospholes reacted with alcohols, ammonia and amines in the presence of sulfur or selenium to form dihydro-1,2,4,3-triazaphosphole 3-chalcogenides. The appropriate difunctional reagents such as glycols, 2-azido alcohols and phenol with a heterodiene function in the ortho position reacted with 2H-1,2,4,3-triazaphospholes to yield products formed via 1,2-addition on P=N bond. Similar behavior is shown by 2-hydroxyacetophenone and 2-hydroxy-benzophenone. 2H-1,2,4,3-Triazaphospholes reacted with acetylenes to form [3+2] cycloadducts; the latter change to 1,2,3-diazaphospholes. [4+1] Cycloadditions occurred with α-diimines, azodicarboxylic esters, and 1,2-diketones; in the latter two cases, the resulting products dimerize.

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New Route for the Synthesis of Hetaryl‐1,5‐benzodiazepines: Part 2

Cited by 3 publications

References 16 publications

1,2,4-Triazines and Their Benzo Derivatives

1,2,4-Triazines and Their Benzo Derivatives

One-Step, Low-Cost, Operator-Friendly, and Scalable Procedure to Synthetize Novel Tetrazolopyrimidinylbenzopyran-2-ones by Benign Protocol

Synthesis and Chemistry of 1,2,4,3-Triazaphosphole Derivatives

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