Silica-ZnCl2 continues to be found to become a competent and eco-friendly

Silica-ZnCl2 continues to be found to become a competent and eco-friendly catalyst for the formation of substituted 4-methylcoumarins from ethyl acetoacetate and substituted phenols under Rabbit Polyclonal to TNAP2. “nice” conditions within an essential oil bath in 80°C. of many chemical substance libraries. A lot of solid-supported reagents like SiO2-SO3H [2] PPA-SiO2 [3] and HClO4-SiO2 [4] have already been developed over the time of time and also have been found in many chemical substance reactions. Inside our laboratory we’ve created many silica-based reagents [5] which fascinated us for the introduction of various other solid-supported reagents. ZnCl2 as an inexpensive and common catalyst continues to be demonstrated in chemical substance reactions being a Lewis acidity catalyst [6]. Though it is normally a consumer choice catalyst it’s very hygroscopic followed using its nonusability. As a result we have ready a silica-ZnCl2 reagent by Paul’s technique [7] that may find application being a user-friendly catalyst. To check on its applicability we wished to utilize this catalyst in the planning of biologically essential molecules whose artificial planning could be improved. Therefore the synthesis was particular by us of substituted coumarins that have more information on applications. Coumarins are located to have mixed bioactivities including inhibition of platelet aggregation [8] inhibition of Masitinib steroid 5a-reductase [9] inhibition of HIV-1 protease [10] and antibacterial [11] and anticancer [12] actions. Suitably substituted coumarins possess several applications in food additives pharmaceutical perfume and cosmetic industries [13]. Moreover 7 derivatives have also been used in the synthesis of dendrimers [14]. Since coumarins have become one of the primary molecules of investigation several groups have started synthesizing molecules with comparable moieties for further applications. Coumarins can be synthesized using several strategies like the Pechmann reaction Perkin reaction and Knoevenagel condensation. The widely used scheme is usually of Pechmann using ethyl acetoacetate and a phenol in the presence of concentrated sulfuric acid as a catalyst [15]. Several other catalysts have also been used including ZnCl2 [16] which involves harsh conditions requires longer time gives smaller yields and entails tedious workup process. Hence a user-friendly protocol for the synthesis of coumarins needs to be developed. In our laboratory we have been synthesizing synthons which are used in the synthesis of biologically important molecules like β-enaminones [17] nitriles [18] formamides [19] and so on. In this Masitinib statement we are presenting a simple and efficient procedure for the synthesis of substituted 4-methylcoumarins using silica-supported ZnCl2 as a heterogeneous catalyst which can acknowledge the advantages of solid-supported catalysts. 2 Experimental 2.1 Materials and Methods Ethyl acetoacetate and substituted phenols were commercial products and were used without Masitinib further purification. Yields refer to yield of the isolated products. Melting points were measured on a RAAGA Indian made melting point apparatus; GC-mass spectra were recorded on a Shimadzu GC-MS QP 5050A instrument. 2.2 Preparation of SiO2-ZnCl2 To a mixture of anhydrous ZnCl2 (3?g) and activated SiO2 (10?g) in a 100?mL round bottomed flask DCM (30?mL) was added and the reaction combination was refluxed for 10?h. SiO2-ZnCl2 was obtained as a free-flowing powder after filtration under reduced pressure and dried at 110°C for 12?h and it was stored in a desiccator over P2O5. 2.3 Common Experimental Masitinib Procedure A mixture of ethyl acetoacetate (2?mmol) phenols (2?mmol) and silica-ZnCl2 (100?mg) was taken in a 50?mL flat-bottomed flask fixed with a condenser mixed well and heated in a preheated oil bath at 80°C for 15-65?min. After completion of the reaction (monitored by TLC) the contents were cooled to 25°C and EtOAc (5?mL) was added to the reaction mixture. The solid catalyst was removed by filtration and washed with dry and warm ethanol and kept aside for reuse. The reaction mixture was washed with water (5?mL) and dried over MgSO4. The solvent was removed under vacuum to get the product. The crude product was further purified either by Masitinib column chromatography or by recrystallization from ethanol?:?water (1?:?1). Yields and physical constants of all the products prepared by this procedure are offered in Table 2. Table 2 Synthesis of coumarin derivatives using ethyl acetoacetate and substituted phenols in the presence of silica-ZnCl2. 3 Results and Conversation As part of our ongoing research program for exploring efficient solid-supported catalysts we used.