A. Batool, Pahlavani Seyyedlary Zahra
Jan 12, 2009
Citations
0
Influential Citations
1
Citations
Journal
Journal of the Iranian Chemical Research
Abstract
Acetylation of hydroxyl groups is a frequently used transformation method in organic synthesis.Among the various protecting groups used for the hydroxyl function, acetyl is the most convenient group in view of its easy introduction, being stable to the acidic reaction conditions, and also easily removable by mild alkaline hydrolysis [1]. Generally, acylation of alcohols and phenols is carried out with carboxylic acids and more conveniently anhydrides or acyl chlorides in the presence of basic catalysts, BrOnsted or Lewis acids and metal salts [2b]. Amongst the catalysts used for activation of anhydrides and acyl chlorides, pyridine [2], EtB3 BN [1], 4(dimethylamino) pyridine (DMAP) [3], Bu B3 BP [4], MgBr B2 B–EtB3 BN [5] and KF–AlB2 BO B3 B[6]P Pare the most significant, whereas HB2 BSO B4 B [7], P-TsOH [8] and NH B2 BSO B3 BH [9] are acidic catalysts. Recently, beside mineral oxides which have proved to be useful to chemists in the laboratory and industry due to the good activation of adsorbed compounds and reaction rate enhancement, selectivity, easier work-up and recyclability of the supports and the eco-friendly, green, reaction conditions [10, 11], other reagents such as distannoxane [12], metal triflates [1315], AlPWB12 BO B40 B[16], ZrClB4 B [17], Cu(BF B4 B) B2 B.6H B2 BO [18], LiClO B4 B [19], ZrOClB2 B.8H B2 BO [20], CeClB3 B [21], BiOClO B4 B.XH B2 BO [22], MgBr B2 B [23], LiCl [24], I B2 B, NBS [25], metal triflates in ionic liquids [15], twisted amides [26], solid supported reagents [27]P Pand Lipase enzymes [28] have been applied for acylation of alcohols and phenols. However, there is always the need for better methods. Recently, La (NO B3 B) B3 B.6H B2 BO has been used as a Lewis acid catalyst for various organic transformations [29, 30]. It is an inexpensive, available and extremely safe reagent to be used in Journal Bof the Iranian Chemical Research