Synthesis of 3-(2-(4-Chlorophenylimino)-3-(4-chlorophenyl)-2,3-dihydrothiazol-4-yl)-2 h-Chromen-2-one via Multicomponent Approach

A simple and highly efficient one-pot, three-component synthesis of 3-(2-(4-chlorophenylimino)-3-(4-chlorophenyl)-2,3-dihydrothiazol-4-yl)-2H-chromen-2-ones has been reported by the reaction of 3-(2-bromoacetyl)-2H-chromen-2-one, primary amines, and phenyl isothiocyanates in presence of dimethylformamide as a solvent. The structures of newly synthesized compounds were confirmed by their analytical and spectral data. GRAPHICAL ABSTRACT


INTRODUCTION
In multicomponent reactions (MCRs) more than two components are assembled into the product in a one-step reaction. The advantages of MCRs are atom economy, simplicity, and time-saving features. These are useful for the synthesis of biologically active compounds such as drugs and agrochemicals, and diversity is achieved easily by varying the components. [1][2][3] Coumarin (benzopyran-2-one) derivatives have found various medicinal applications as antibacterial, [4,5] antifungal, [6,7] herbicidal, [8] antitumoral, [9] cytotoxic, [10] and anti-HIV agents. [11,12] The compounds containing the coumarin motif are widely used as additives in food and cosmetic products and known as luminescent materials. [13] They also act as anticoagulants, [14] free radical scavengers, [15] antioxidant, [16] lipoxygenase, [17] and cyclooxygenase inhibitors. [18] Heterocyclic systems having nitrogen and sulfur are very interesting because of their physicochemical properties with relevance to the design of new drugs. In particular the thiazoline ring system has attracted considerable attention because of its presence in several drug molecules with different biological activities such as antifungal, [19] anti-inflammatory, [20] anti-HIV, [21] analgesic, kinase inhibition, [22] and melanin-reducing activity. [23] These are also applied in agriculture as acricides, insecticides, and plantgrowth regulators.
Our current studies are focused on the development of new routes for the synthesis of thiazol-2-imine incorporating coumarin moieties.
The mechanism for the formation of these products is discussed in Scheme 2. In this procedure we have modified the known Hantzsch method for thiazole synthesis involving the reaction of phenyl isothiocyanates, primary amines, and 3-(2-bromoacetyl)-2H-chromen-2-one compounds. In the literature [24] the synthesis of 3-(4-phenyl thiazoline-2-anil)-2H-1-benzopyran-2-ones 9 by the condensation of 3-(2-bromoacetyl)-2H-chromen-2-ones 1 with symmetrical thiourea such as diphenylthiourea 8 (Scheme 3) has been reported. As the scope for the synthesis of these compounds is rather limited, we tried to develop the present one-pot multicomponent synthesis of the title compounds. This procedures may find extensive applications in the synthesis of a wide variety of substituted thiazolines. This procedure is

EXPERIMENTAL
All the reagents and solvents were pure, purchased from commercial sources, and used without further purification unless otherwise stated. 3-(2-Bromo-acetyl)-2H-chromen-2-ones were prepared by the literature procedure. [25] Melting points were determined in open capillaries with a Cintex melting-point apparatus (Mumbai, India) and were uncorrected. CHN analysis was carried out by Carlo Erba EA 1108 automatic elemental analyzer. The purity of the compounds was checked by thin-layer Scheme 3. Literature method.

SUPPLEMENTAL MATERIAL
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