Yttria-Zirconia Based Lewis Acid: An Efficient and Chemoselective Catalyst for Acylation Reactions

Abstract

Yttria-zirconia based strong Lewis acid efficiently catalyzes acylation of alcohols, amines and thiols under environmentally safe, heterogeneous reaction conditions with high selectivity and in excellent yields.

Decatungstodivanadogermanic heteropoly acid (H6GeW10V2O40.22H2O): A novel, green and reusable catalyst for efficient acetylation of alcohols and phenols under solvent-free conditions

“…The unsaturated alcohol such as cinnamyl alcohol was selectively converted to the corresponding acetate and the carbon-carbon double bond remained intact under the reaction conditions (Table 2, entry 19). Aliphatic and nonbenzylic alcohols were also converted into the corresponding acetate compounds with high efficiency under the same reaction conditions (Table 2, entries [20][21][22][23][24][25]. It is noteworthy that sterically hindered tertiary alcohols, such as triphenylmethanol, also can be acetylated with high yield but it takes a longer reaction time (Table 2, entry 26).…”

“…Heterogeneous catalysts offer several advantages over homogeneous systems with respect to easy recovery and recycling of catalysts as well as the minimization of undesired toxic wastes. In this framework, several metal oxides and supported systems including YO2-ZrO2 [22], ZnO [23], transition metal oxides [24], montmorillonites [25], HClO4-SiO2 [26], H2SO4-SiO2 [27], AlPW12O40 [28], zeolites [29], Nafion-H [30], HBF4-SiO2 [31], KF-Al2O3 [32], MoO3-Al2O3 [33], NaHSO4-SiO2 [34], sulphated zirconia [35] and (NH4)2.5H0.5PW12O40 [36] [TMBSA][HSO4] ionic liquid [37], silica-bonded cobalt(II) salen [38], and silica-bonded N-propyl sulfamic acid and S-propyl sulfuric acid [39,40] have been used as heterogeneous catalysts for the acetylation of alcohols and phenols. However, each of these methods has advantages and limitations.…”

Highly Efficient and Versatile Acetylation of Alcohols, Phenols and Amines Catalyzed by Methylenediphosphonic Acid (Mdp) Under Solvent-Free Conditions

“…The most commonly used reagent combination for this reaction uses an acid anhydride in the presence of an acid or base catalyst 2 . The various catalysts developed for acetylation include the use of Bu 3 P 3 , metal triflates such as Sc(OTf) 3 4 , TMSOTf 5 , Sc(NTf 2 ) 3 6 , Cu(OTf) 2 7 , In(OTf) 3 8 , Bi(OTf) 3 9 , ZrO(OTf) 2 10 ; p-toluenesulfonic acid 11 , Nafion-H 12 , Montmorillonite K-10 and KSF clay 13 , yttria-zirconia 14 21 . The catalysts suffer from certain drawbacks.…”

1,1'-(Ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) as a recyclable catalyst for acylation

“…17,18 Metal triflates [19][20][21][22][23][24][25][26][27][28][29] and perchlorates [30][31][32][33] have been used for the purpose owing to their acidic nature. Other reagents / catalysts employed are TMSCl, 34 HClO 4 -SiO 2,35 Sc(NTf 2 ) 3,36 Nafion-H, 37 Yttria-Zirconia, 38 43 Although metal triflates, perchlorates and other acidic catalysts are effective for the acylation reaction, their use is limited due to explosive nature of metal perchlorates and strong acidic character of triflates which results in side reactions. The drawbacks associated with some of the procedures reported in literature are arduous preparation of catalysts, difficulties in work-up and isolation, the need for an inert atmosphere, harsh reaction conditions, expensive reagents, low yields, longer reaction times, dry solvents and incompatibility with other protecting groups.…”