Scandium Trifluoromethanesulfonate as an Extremely Active Lewis Acid Catalyst in Acylation of Alcohols with Acid Anhydrides and Mixed Anhydrides

Abstract

Scandium trifluoromethanesulfonate (triflate), which is commercially available, is a practical and useful Lewis acid catalyst for acylation of alcohols with acid anhydrides or the esterification of alcohols by carboxylic acids in the presence of p-nitrobenzoic anhydrides. The remarkably high catalytic activity of scandium triflate can be used for assisting the acylation by acid anhydrides of not only primary alcohols but also sterically-hindered secondary or tertiary alcohols. The method presented is especially effective for selective macrolactonization of omega-hydroxy carboxylic acids.

Tandem Catalysis: The Sequential Mediation of Olefin Metathesis, Hydrogenation, and Hydrogen Transfer with Single-Component Ru Complexes

“…After 8 h at room temperature, the resulting yellow solution was diluted with water (15 mL) and extracted with Et 2 O (3 x 10 mL). After concentrating the organic layer to a yellow oil, purification via column chromatography (silica gel, hexanes/ethyl acetate as S5 eluent) afforded 3-allyloxy-5-(2-methallyloxy)-cyclopentene (18) …”

Efficient Protection of Alcohols with Carboxylic Acids Using a Variety of Heteropolyoxometallates as Catalysts, Studying Effective Reaction Parameters

“…A number of reagents coupled with different catalysts have been put forth for the protection of alcohols. Protection of alcohols is usually performed employing acid anhydrides or acyl chlorides in the presence of stoichiometric amounts of protonic and Lewis acids, such as p-toluenesulfonic acid, 1 scandium trifluromethanesulfonate, 2 trimethylsilyl triflouromethanesulfonate, 3 zinc chloride, 4 and cobalt chloride. 5 The above options employing acetic anhydride as acetylating agent and soluble acids as reagents or catalysts presents achieve less than 50% atom economy in the consumption of acetic anhydride by utilizing only the acetyl group.…”

Zinc dust: An extremely active and reusable catalyst in acylation of phenols, thiophenol, amines and alcohols in a solvent-free system

“…Acylation with acids [8,9], acyl imidazoles [10], and acyl urea [11], are also known. Acid catalyzed acylation mainly requires polymeric acids [12,13]; and metal chlorides [14][15][16], metal triflates such as Sc(OTf)3/Bi(OTf)3/Li(OTf)3 [17][18][19], metal perchlorates (LiClO4 /BiOClO4) [20,21] have also been utilized as Lewis acid catalysts for acylation of alcohols. Other reagents such as I2 [22,23], [bmIm][dca] ionic liquid [24], solid supported reagents like HClO4-SiO2 [25], Py/basic alumina [26], neutral Al2O3 [27], Clay [28,29], ZrOCl2·8H2O [30] polyphosphate ester [31] and very recently ZnO [32], Sm [33] and Mg(NTf2)2 [34] have been employed for the same purpose.…”