Synthesis of 2-Aminobenzothiazolomethyl Naphthols Using l-Valine Organocatalyst: An Efficient, Versatile and Biodegradable Catalyst

Abstract

A simple, practical and scalable approach for the synthesis of 2-aminobenzothiazolomethyl naphthols using one-flask threecomponent reaction of 2-aminobenzothiazole, substituted aromatic aldehydes and β-naphthol in water is reported. The reaction is catalyzed by l-valine as non-toxic, green, easily available, cheap, sustainable and biodegradable catalyst. The product formation takes shorter reaction time with good to excellent yield. The method is demonstrated on multi gram level. Easy workup procedure, short reaction time and most importantly environmentally benign are the most outstanding advantages of this procedure.

Untitled

“…Thus, a series of methodologies have been explored to prepare aminoalkyl naphthols through more efficient procedures (especially one-pot multicomponent reactions) to overcome the drawbacks of classical synthetic routes [9][10][11][12]. The synthesis by using 2-naphthol, aldehydes, and amines has been performed by various catalytic systems including (+)-camphor-10sulfonic acid [13], Fe3O4@SiO2-ZrCl2-MNPs [14], maltose [15], oxalic acid [16], ionic liquid [17], aragonite [18], NH3(CH2)5NH3BiCl5 [19], and l-Valine [20]. However, these procedures and catalysts suffer from several drawbacks such as toxicity, long reaction time, vigorous conditions, tedious work-up, nonrecoverability, and non-reproducibility.…”

Convenient Approach for the Synthesis of 2-Aminobenzothiazolomethyl Naphthols Using Trisodium Citrate Dihydrate as Green Catalyst Under Microwave Irradiations

“…2-Aminobenzothiazoles are highly reactive compounds and used as reactants or reaction intermediates to synthesize a wide variety of biologically active fused heterocyclic compounds and in other organic transformations (Erian, 1993). In recent years, various procedures have been exist in literature for the synthesis of 2-aminobenzothiazolomethyl naphthol derivatives by adopting one-pot multi-component reactions (Hulme et al, 2009) (Jiang et al, 2010) (Dömling et al, 2012), like Agar (Moradi et al, 2015), Citric acid (Lashkari et al, 2016), Fe3O4@SiO2-ZrCl2-MNPs (Kamali and Shirini, 2018), Fumaric acid (Maghsoodlou et al, 2016), Graphite-supported (HClO4-C) (Lei et al, 2013), Grindstone (Mohan et al, 2015), Heteropoly acids (Javanshir et al, 2014), Ionic liquids (Yu and Guo, 2011), L-valine (Lal et al, 2020), Magnetic nanocatalyst (Lati et al, 2018), Maltose (Adrom et al, 2015), Microwave irradiations (Niralwad et al, 2011), Ionic liquid (Shaterian and Hosseinian, 2014), NaHSO4.H2O (Shaterian and Mohammadnia, 2013), NBS (Hosseinian and Shaterian, 2012), Phosphate Fertilizers (Li et al, 2013), Sodium dodecyl sulfate (Zimou et al, 2019), Sphalerite (Lal, 2015), Trichloroisocyanuric acid (Kumar et al, 2010), Wells-Dawson heteropoly acid (Yang L., 2012), Zinc oxide micelles (Ohanian et al, 2009), γ-Aminobutyric acid and collagen peptides biocatalyst (Mou et al, 2017) and heterogenous phosphate catalysts (Fardpour et al, 2018).These reported protocols produce good yields of the products in many instances (Shaabani et al, 2007). However, some of the synthetic protocols undergo with certain limitations such as use of very expensive catalysts, solvents, large amount of catalyst, low yields of products, long reaction times, tedious procedures for preparations of catalysts and tedious workup conditions.…”