- Open Access
NaHSO4-SiO2 as an efficient and chemoselective catalyst, for the synthesis of acylal from aldehydes under, solvent-free conditions
© PERURI et al.; licensee Chemistry Central Ltd. 2012
Received: 14 August 2012
Accepted: 7 September 2012
Published: 13 November 2012
Structurally diverse aldehydes are successfully converted into acylals (1,1-diacetates) with acetic anhydride using NaHSO4-SiO2 as a mild, convenient and inexpensive catalyst under solvent-free conditions. The noteworthy features of the present system are shorter reaction times, and mild and solvent-free conditions. Furthermore, it offers chemoselective protection of aldehydes.
Both aromatic and aliphatic aldehydes reacts smoothly with acetic anhydride in presence of silica supported sodium hydrogen sulphate to afford the corresponding 1,1-diacetates in good to excellent yields. We studied competitive reactions for the acylation of aldehydes in the presence of ketones using silica supported sodium hydrogen sulphate as a catalyst. Using this catalytic system, the highly selective conversion of an aldehyde in the presence of ketone was observed.
NaHSO4-SiO2 is a chemoselective and highly efficient catalyst for acylal formation from aldehydes. The advantages of this methodology over the reported methods is the availability of the starting materials, simplicity of acylation procedure, a clean work-up, a short reaction time, high yields and reusability.
The concept of green chemistry has been playing an important role in recent years for meeting the fundamental scientific challenges of protecting the living environment. One of the thrust areas for achieving this target is to explore alternative reaction conditions and reaction media to accomplish the desired chemical transformation with almost negligible by products and waste generation as well as elimination of the use of volatile and toxic organic solvents. It is therefore of utmost importance to evolve a simple and effective methodology for the different organic transformations that cover the concept of green chemistry.
During the multi-step synthesis, the protection of the carbonyl group is widely achieved by the formation of acylal (1,1-diacetate) . These substrates are important because of their application as precursors for the synthesis of 1-acetoxy dienes, valuable synthetic intermediates for Diels-Alder cycloaddition reactions . The relative acid stability of acylal is another interesting feature in the field of protection and deprotection chemistry. General, acylals are prepared by treating aldehydes with acetic anhydride in the presence of protonic acids , Lewis acids , heteropoly acids, or clays . Some examples of the reagents and catalysts that have been developed for this purpose include LiOTf , ceric ammonium nitrate , InCl3 , H2NSO3H , LiBF4 , H2SO4 , PCl3 , NBS , I2 , TMSCl-NaI , FeCl3 , Fe2(SO4)3.xH2O , Zn(BF4)2 , Cu(BF4)2.xH2O , H2SO4-SiO2 , Silica sulphate . Although some of these methods have convenient protocols with good to high yields, the majority of these methods suffer at least from one of the following disadvantages: reaction under oxidizing conditions, prolonged reaction time, high temperatures, use of moisture-sensitive and expensive catalysts, use of solvents, strong conditions, difficulty in scaling up, etc. Therefore, development of catalysts working under mild reaction conditions is desirable.
In recent years, Heterogeneous catalysts have gained importance in several organic transformations due to their interesting reactivity as well as for economic and environmental reasons. In continuation of our research work to develop new methodologies for organic transformations, [22–25] we observed that silica supported sodium hydrogen sulphate is a highly efficient catalyst for the synthesis of 1,1-diacetates (acylals) from the reaction of aldehydes with acetic anhydride under solvent-free conditions. The catalyst NaHSO4-SiO2 can easily be prepared  from the readily available NaHSO4 and silica gel (230–400 mesh) and these are inexpensive and nontoxic as the reaction is heterogeneous in nature, so the catalyst can easily removed by simple filtration.
Results and discussions
Formation of acylals using NaHSO 4 -SiO 2 under solvent-free conditions at rt a
The synthesis of acylal from benzaldehyde and acetic anhydride in the presence of recycled NaHSO 4 -SiO 2
The recycling of the catalyst is one of the most advantages of our method. For the reaction of benzaldehyde with acetic anhydride good yield was observed when NaHSO4-SiO2 was reused even after three times recycling (Table 2).
In conclusion, NaHSO4-SiO2 is a chemoselective and highly efficient catalyst for acylal formation from aldehydes. The advantages of this methodology over the reported methods is the availability of the starting materials, simplicity of acylation procedure, a clean work-up, a short reaction time, and high yields. In addition, this reagent acts as a heterogeneous catalyst that could be removed from the reaction mixture by simple filtration and compliance with the green chemistry protocols.
All 1 H NMR spectra were recorded on 400 MHz Varian FT-NMR spectrometers. All chemical shifts are given as δ value with reference to Tetra methyl silane (TMS) as an internal standard. Melting points were taken in open capillaries. The IR spectra were recorded on a PerkinElmer 257 spectrometer using KBr discs. Products were purified by flash chromatography on 100–200 mesh silica gel. The chemicals and solvents were purchased from commercial suppliers either from Aldrich, Spectrochem and they were used without purification prior to use. The obtained products were characterized from their spectral (1 H-NMR, IR) and comparison to authentic samples.
Preparation of silica supported sodium hydrogen sulphate
To a solution of 4.14 g (0.03 mol) of NaHSO4.H2O in 20 mL of water in a 100 mL beaker containing a stir bar was added 10 g of SiO2 (column chromatographic grade, 230–400 mesh). The mixture was stirred for 15 min and then gently heated on a hot plate, with intermittent swirling, until a free-flowing white solid was obtained. The catalyst was further dried by placing the beaker in an oven maintained at 120 °C for at least 48 h prior to use.
General experimental procedure
A mixture of aldehyde (2 mmol), freshly distilled Ac2O (8 mmol) and NaHSO4-SiO2 (25%/wt) was stirred at room temperature and the progress of the reaction was monitored by TLC Hexane: EtOAc (9:1) after completion of the reaction, the reaction mixture was treated by dilution with EtOAc and the catalyst was removed by filtration. Obtained filtrate was washed with saturated NaHCO3 solution and water and then dried over Na2SO4. The solvent was evaporated under reduced pressure to get the crude product was purified by column chromatography to give pure acylal compound.
Selected spectral data of the products
Phenylmethylene diacetate (Table 1, Entry-1)
1 H NMR (CDCl3): δ7.63(s, 1 H), 7.53-7.50 (m, 2 H), 7.40-7.36 (m, 3 H), 2.11 (s, 6 H); IR (KBr, cm-1): 3068, 1756, 1504, 1440, 1010; Anal. Calcd. For C11H12O4: C, 63.45; H, 5.81. Found: C, 63.71; H, 5.70.
(4-chlorophenyl) methylene diacetate (Table 1, Entry-2)
1 H NMR (CDCl3): δ7.63 (s, 1 H), 7.46 (d, J = 8.4 Hz, 2 H), 7.38 (d, J = 8.4 Hz, 2 H), 2.12 (s, 6 H); IR (KBr, cm-1): 3019, 2924, 1769, 1745, 1492, 1373, 1241, 1070, 1006; Anal. Calcd. For C11H11ClO4; C, 54.45; H, 4.57. Found: C, 54.36; H, 4.68.
(4-methoxyphenyl) methylene diacetate (Table 1, Entry-6)
1 H NMR (CDCl3): δ7.62 (s, 1 H), 7.45 (d, J = 8.8 Hz, 2 H), 6.92 (d, J = 8.8 Hz, 2 H), 3.82 (s, 3 H), 2.11 (s, 6 H); IR (KBr, cm-1): 3014, 2937, 1749, 1618, 1378, 1244, 1207, 1018, 936; Anal. Calcd. For C12H14O5; C, 60.50; H, 5.92. Found: C, 60.98; H, 5.66.
We sincerely thank the RA chem. Pharma Ltd for financial support and encouragement. Support from the analytical department is also acknowledged.
- Greene TW, Wuts PGM: Protective groups in organic synthesis. 1999, New York: John Wiley, 306-3rdView ArticleGoogle Scholar
- Snider BB, Amin SG: An Improved Synthesis of 1α, 3β-Dihydroxycholesta-5, 7-Diene. Synth Commun. 1978, 8: 117-125. 10.1080/00397917808062105.View ArticleGoogle Scholar
- Tomita M, Kikuchi T, Bessho K, Hori T, Inubushi Y: Studies on Pilocereine and Related Compounds. III. Synthesis of 2, 2', 3-Trimethoxydiphenyl Ether-4', 5- and -4', 6-dicarboxaldehyde. Chem Pharm Bull. 1963, 11: 1484-1490. 10.1248/cpb.11.1484.View ArticleGoogle Scholar
- Man EH, Sanderson JJ, Hauser CR: Boron Fluoride Catalyzed Addition of Aliphatic Anhydrides to Aldehydes. J Am Chem Soc. 1950, 72: 847-847. 10.1021/ja01158a053.View ArticleGoogle Scholar
- Kumar R, Tiwari P, Maulik PR, Misra AKJ: HClO4-SiO2 catalyzed chemoselective synthesis of acylals from aldehydes under solvent-free conditions. Mol Catal A Chem. 2006, 247: 27-30. 10.1016/j.molcata.2005.11.019.View ArticleGoogle Scholar
- Karimi B, Maleki JJ: Lithium Trifluoromethanesulfonate (LiOTf) as a Recyclable Catalyst for Highly Efficient Acetylation of Alcohols and Diacetylation of Aldehydes under Mild and Neutral Reaction Conditions. J Org Chem. 2003, 68: 4951-4954. 10.1021/jo026678+.View ArticleGoogle Scholar
- Roy SC, Banerjee B: A Mild and Efficient Method for the Chemoselective Synthesis of Acylals from Aldehydes and their Deprotections Catalysed by Ceric Ammonium Nitrate. Synlett. 2002, 10: 1677-1678.View ArticleGoogle Scholar
- Yadav JS, Reddy BVS, Srinivas C: Indium tri chloride catalyzed chemoselective conversion of aldehydes to gem diacetates. Synth Commun. 2002, 32: 2149-2153.View ArticleGoogle Scholar
- Jin TS, Sun G, Li YW, Li TS: An efficient and convenient procedure for the preparation of 1,1-diacetates from aldehydes catalyzed by H2NSO3H. Green Chem. 2002, 4: 255-256. 10.1039/b200219a.View ArticleGoogle Scholar
- Sumida N, Nishioka K, Sato T: Conversion of Aldehydes into Geminal Dicarboxylates (Acylals) Catalyzed by Lithium Tetrafluoroborate. Synlett. 2001, 12: 1921-1922.View ArticleGoogle Scholar
- Gregory MJ: Evidence for a cyclic AA11 mechanism in the hydrolysis of benzylidene diacetates. J Chem Soc. 1970, B: 1201-1207.Google Scholar
- Michie JK, Miller JA: Phosphorus Trichloride as Catalyst in the Preparation of 1,1-Diacetates from Aldehydes. Synthesis. 1981, 10: 824-825.View ArticleGoogle Scholar
- Karimi B, Seradj H, Ebrahimian RG: Mild and Efficient Conversion of Aldehydes to 1,1-Diacetates Catalyzed with N-Bromosuccinimide (NBS). Synlett. 2000, 5: 623-624.Google Scholar
- Deka N, Kalita DJ, Borah R, Sarma JCJ: Iodine as Acetylation Catalyst in the Preparation of 1,1-Diacetates from Aldehydes. Org Chem. 1997, 62: 1563-1564. 10.1021/jo961741e.View ArticleGoogle Scholar
- Deka N, Borah R, Kalita DJ, Sarma JC: Synthesis of 1,1-Diacetates from Aldehydes using Trimethylchlorosilane and Sodium Iodide as Catalyst. J Chem Res. 1998, 94-95. SGoogle Scholar
- Kochhar KS, Bal BS, Deshpande RP, Rajadhyaksha SN, Pinnick HWJ: Protecting groups in organic synthesis. Part 8. Conversion of aldehydes into geminal diacetates. J Org Chem. 1983, 48: 1765-1767. 10.1021/jo00158a036.View ArticleGoogle Scholar
- Zhang X, Li L, Zhang G: An efficient and green procedure for the preparation of acylals from aldehydes catalyzed by Fe2(SO4)3·xH2O. Green Chem. 2003, 5: 646-648. 10.1039/b305772k.View ArticleGoogle Scholar
- Ranu BC, Dutta J, Das A: Zinc Tetrafluoroborate-Catalyzed Efficient Conversion of Aldehydes to Geminal Diacetates and Cyanoacetates. Chem Lett. 2003, 32: 366-367. 10.1246/cl.2003.366.View ArticleGoogle Scholar
- Chakaraborti AK, Thilagavathi R, Kumar R: Copper(II) Tetrafluoroborate-Catalyzed Formation of Aldehyde-1,1-diacetates. Synthesis. 2004, 6: 831-833.View ArticleGoogle Scholar
- Pourmousavi SA, Zinati Z: H2SO4-silica as an efficient and chemoselective catalyst for the synthesis of acylal from aldehydes under solvent-free conditions. Turk J Chem. 2009, 33: 385-392.Google Scholar
- Kumar RK, Satyanarayana PVV, Reddy SB: Simple and Efficient Method for Tetrahydropyranylation of Alcohols and Phenolsby Using Silica Supported Sodium Hydrogen Sulphate as a Catalyst. Asian J Chem. 2012, 24: 3876-3878.Google Scholar
- Jin TS, Zhao Y, Gu SQ, Liu LB, Li TS: An efficient procedure for the synthesis of 1,1-diacetates from aldehydes with acetic anhydride catalyzed by silica sulfate. Indian J Chem 45B. 2006, 4: 1054-1056.Google Scholar
- Kumar RK, Satyanarayana PVV, Reddy SB: Simple and Efficient Method for Deprotection of Tetrahydropyranyl Ethers by Using Silica Supported Sodium Hydrogen Sulphate. Chin J Chem. 2012, 30: 1189-1191. 10.1002/cjoc.201100358.View ArticleGoogle Scholar
- Kumar RK, Satyanarayana PVV, Reddy SB: Direct and practical synthesis of 2-Arylbenzoxazoles promoted by Silica supported sodium hydrogen sulphate. Der Pharma Chemica. 2012, 4 (2): 761-766.Google Scholar
- Kumar RK, Satyanarayana PVV, Reddy SB: NaHSO4-SiO2 promoted synthesis of Benzimidazole derivatives. Arch Appl Sci Res. 2012, 4 (3): 1517-1521.Google Scholar
- Breton GW: Selective Monoacetylation of Unsymmetrical Diols Catalyzed by Silica Gel-Supported Sodium Hydrogen Sulfate. J Org Chem. 1997, 62: 8952-8954. 10.1021/jo971367y.View ArticleGoogle Scholar
- Heravi MM, Bakhtiari K, Taheri S, Oskooie HA: KHSO4: a catalyst for the chemo-selective preparation of 1,1-diacetates from aldehydes under solvent-free conditions. Green Chem. 2005, 7: 867-869. 10.1039/b510855c.View ArticleGoogle Scholar
- Hajipour AR, Khazdooz L, Ruoho AE: Brönsted acidic ionic liquid as an efficient catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions. Catal Commun. 2008, 9: 89-96. 10.1016/j.catcom.2007.05.003.View ArticleGoogle Scholar
- Khan AT, Choudhury LH, Ghosh SJ: Silica supported perchloric acid (HClO4-SiO2): A highly efficient and reusable catalyst for geminal diacylation of aldehydes under solvent-free conditions. Mol Catal A Chem. 2006, 255: 230-10.1016/j.molcata.2006.04.008.View ArticleGoogle Scholar
- Saini A, Kumar S, Sandhu JS: RuCl3xH2O: A New Efficient Catalyst for Facile Preparation of 1,1‐Diacetates from Aldehydes. Synth Commun. 2007, 38: 106-113. 10.1080/00397910701650831.View ArticleGoogle Scholar
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