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Chemoselective Synthesis of 1,1-Diacetates from Aldehydes in the Presence of Al(HSO4)3 under Mild Solvent-Free Conditions.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Mirjalili, Bi Bi Fatemeh Zolfigol, Mohammad Ali Bamoniri, Abdolhamid Amrollahi, Mohammad Ali Sheikhan, Nafisehsadat |
| Copyright Year | 2007 |
| Abstract | A novel efficient procedure has been developed for the preparation of acylals in high yields by reaction of the corresponding aldehydes with acetic anhydride in the presence of Al(HSO4)3 as catalyst under mild (room temperature) solvent-free conditions. * The text was submitted by the authors in English. Acylals attract interest as an alternative to acetals for the protection of aldehyde group due to their stability in basic and neutral media. From the synthetic viewpoint, 1,1-diacetates are important as precursors of 1-acetoxy dienes for Diels–Alder reactions [1] and intermediate products in various transformations, including nucleophilic substitution reactions [2–6]. Known syntheses of acylals from aldehydes and acetic anhydride involve strong protic acids, such as sulfuric, methanesulfonic, and phosphoric, and Lewis acids, e.g., WCl6 [7] or ZrCl4 [8]. In the recent years, several reagents and catalysts have been proposed, in particular P2O5/SiO2 [9], NBS [10], Bi(NO3)3 · 5H2O [11], In(OTf)3 [12], Bi(OTf)3 · x H2O [13], zirconium sulfophenyl phosphonate [14], H2NSO3H [15], LiBF4 [16], zinc montmorillonite [17], and heteropolycompounds such as Wells–Dawson acid [18] or aluminum dodecatungstophosphate [19]. According to recently reported data, many reactions proceed more effectively in the solid state than in solution. Solvent-free techniques offer such advantages as reduced pollution, low cost, simplicity of handling, and easy workup. These factors are especially important for large-scale processes. Analogous advantages (specifically, reduced reactor and plant corrosion and environmentally safe disposal) are inherent to the use of solid acids instead of, e.g., sulfuric acid. Inorganic acidic salts such as Al(HSO4)3 [20, 21] may be recommended as reagents and catalysts in the above reactions. Although publications on the use of these salts in synthetic practice are few in number, in the recent years more attention has been given to their synthetic potential in organic chemistry. To the best of our knowledge, there are no published data on the synthesis of acylals with the aid of Al(HSO4)3. Aluminum(III) hydrogen sulfate is a stable nonhygroscopic crystalline substance that is insoluble in most organic solvents. In continuation of our studies on the application of metal hydrogen sulfates in organic synthesis, the present communication describes a convenient method for the preparation of acylals from the corresponding aldehydes and acetic anhydride in the presence of Al(HSO4)3. The reactions were carried out at room temperature without a solvent using 4–9 mol % of the catalyst (Scheme 1, see table). DOI: 10.1134/S1070428007060085 |
| Starting Page | 852 |
| Ending Page | 854 |
| Page Count | 3 |
| File Format | PDF HTM / HTML |
| DOI | 10.1002/chin.200750052 |
| Alternate Webpage(s) | https://page-one.springer.com/pdf/preview/10.1134/S1070428007060085 |
| Alternate Webpage(s) | https://doi.org/10.1002/chin.200750052 |
| Volume Number | 38 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
