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Heterogeneous catalysis holds many potentials for replacing reagents in the field of green chemistry and environment protection. Yttria zirconia based heterogeneous catalysis shows the Lewis acid catalytic properties and play a vital role in the synthesis of an intermediate 5-chloro-2, 3-dihydro-1H- inden-1-one with high yield and selectivity.

This prompted us to synthesize 5-chloro-2,3-dihydro-1H-inden-1-one using green catalyst, and here we report that an yttria-zirconia based Lewis acid serves as an excellent catalyst for the selective cyclisation of 5-chloro-2,3-dihydro-1H-inden-1-one during . T Aimed to develop an application of green catalyst in synthetic organic chemistry, the Yttria-zirconia based acidic was found to be an extremely efficient catalyst for the Diels Alder 22-28 reaction and Tran’s esterification 23-28 of b- keto esters 24. However, the reaction of 5-chloro-2,3-dihydro-1H-inden-1-one with Aluminum chloride or potassium fluoride is found to be sluggish with solvent andcatalyst (Table 1, entries 2) and reaction with solvent and catalyst (20 mol %) gives better yield and selectivity of the product. (Table 1, entries 2)

Procedure for the preparation of the catalyst: The catalyst prepared using a mixture of aqueous solutions of yttrium nitrate and zirconyl nitrate (molar ratio 16:84) with aqueous ammonia (28%) under vigorous stirring until a pH value of 8-8.5 was achieved and a precipitate was formed. Downloaded by: National University of Singapore. Copyrighted material. LETTER Yttria-Zirconia Based Lewis Acid 209 , Synlett 2001, No. 2, 206–209 ISSN 0936-5214 © Thieme Stuttgart · New York. Precipitate was washed with deionized water, dried at 110°C, treated with 2N sulfuric acid, dried again at 120°C for 24 h. The subsequent programmed calcination at 500°C for 3 h at a heating rate of 2°C min- 1 resulted in a highly acidic material. (a) 5-chloro-2,3-dihydro-1H-inden-1-one In a typical experimental procedure, compound 1 (20 mmol; 1.0 equiv) was added in toluene 20 ml of dry toluene and followed by addition of catalyst (10 % by weight), and the mixture was heated refluxed for 100-110 oC the indicated length of time (Table 1–2). The progress of the reaction monitored by monitored by TLC. After completion of reaction, the catalyst was filtered and kept aside for recycling purpose. Filtrate mother liquor diluted with water (30 ml). The organic layer was separated, washed with 10 % aq. NaHCO3, brine followed by water and dried over Na2SO4. The solvent was removed and the crude product was chromatographed on a silica gel column to afford the pure product using hexane ethyl acetate (9: 1). After the reaction, the catalyst is recovered with retention of its catalytic activity. It can be further reactivated for reuse by heating it at 500 °C in the presence of air. The substrates examined in our studies and the results obtained are summarized in Table 1 and table 2. Table1: Experimental detail of 5-chloro-2,3-dihydro-1H-inden-1-one from 3-chlorophenyl propionic acid using green Yttria zirconia based heterogeneous catalysis are summarized in below table.

Product were characterized by 1H NMR CDCl3 2.47 (3H, S), 6.38-6.40 (2H, dd), 7.22-7.26(2H, dd), 9.48 OH (bs) and

IR in cm-1: ; C=O peaks 1715 cm-1, OH peak 2400 cm-1, Mass spectrum MS+1, (167) and its correspond to the authentic sample 28.

The Experimental details are summarized in Table-1  & Table-2
Table1: Experimental detail of 5-chloro-2,3-dihydro-1H-inden-1-one from 3-chlorophenyl propionic acid  using green Yttria zirconia based heterogeneous catalysis are summarized in below table.

Isolated yield:*b Column chromatography *** NA: Not applicable 
Table 2. Summary of experimental detail with respect to variation of catalyst mol % / time/ temperature verses % Yield. 

Isolated yield:*b Column chromatography *** NA: Not applicable 

Sample analyzed  and matched with Authentic samples using NMR , IR 

The literature showed highly corrosive, hazardous and polluting conventional liquid acids and Lewis acids such as Phosphoric acid, PPA, nitric acid, H2SO4, HCl, HF, HClO4, H3PO4, AlCl3, BF3, ZnCl2 to overcome the above process. We have plan to synthesize using Green catalyst. Which gives high selectivity, easy work procedure and high yield > 98 % in very short span of time.

Yttria zirconia based green catalyst approach towards synthesis of 5-chloro-2,3-dihydro-1H-inden-1-one from 3-chlorophenyl propionic acid shown better catalytic properties with respect to the selectivity and easy workup procedure. These solid acid catalysts having strong incentives to which one can replace the unfriendly AlCl3/H2SO4 and HF acids in many industrial processes, and in this direction, there is a lot of scope and advantage to work. Catalytic activity of these catalysts depends on the method of preparation, precursors used, nature of promoting agents, calcination temperature etc. But still there is tremendous scope to study and exploit these catalysts for numerous reactions as a green chemistry.

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