NaHSO4-SiO2 as an efficient and chemoselective catalyst, for the synthesis of acylal from aldehydes under, solvent-free conditions

Abstract

BackgroundStructurally 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.ResultsBoth 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.ConclusionsNaHSO4-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.

Synthesis and hybridizing properties of P-stereodefined chimeric [PS]-{DNA:RNA} and [PS]-{DNA:(2′-OMe)-RNA} oligomers

“…Detritylation was carried out in anhydrous acetonitrile using a sodium hydrogen sulfate suspension deposited on silica gel. 31 The crystal structure was resolved ( Fig. 1 ) with the refinement parameter R = 0.0563 and ESI.…”

P-Stereodefined phosphorothioate analogs of glycol nucleic acids—synthesis and structural properties

“…To a solution of 5a (100 mg) in CH 3 CN (10 mL) a catalytic amount of NaHSO 4 /SiO 2 (prepared according to ref. 38 ) was added.…”

Microwave-assisted green synthesis of 1,1-diacetates (acylals) using selectfluor™ as an environmental-friendly catalyst under solvent-free conditions

“…Therefore, the methods for their synthesis have received considerable attention. Usually, the preparation of 1,1-diacetates has been achieved by the reaction of aldehydes with acetic anhydride in the presence of different catalysts and under microwave irradiation such as SBA-15-Ph-PrSO 3 H [6], Fe 3 O 4 @SiO 2 [7], PEG-SO 3 H [8], Poly(4-vinylpyridinium) perchlorate [9], TiCl 4 [10], N-Sulfonic acid poly(4-vinylpyridinum) hydrogen sulfate [11], NaHSO 4 -SiO 2 [12], H 2 SO 4 -silica [13], SbCl 3 [14], 1,3-Dibromo-5,5-dimethylhydantoin [15], Silica-supported functional ionic liquid (Si- [SbSipim][PF6]) [16], ZSM-5-SO 3 H [17], Amberlyst-15 [18], Zirconium hydrogen sulfate [19] Bismuth triflate [20], Iron(III) fluoride [21] and etc. Although some of these methods 1,1-diacetates are obtained in good to high product yields suffer from some disadvantages such as long reaction time, require high temperature, tedious work-up procedure, the use of homogenous catalysts or harmful solvents, expensive and highly toxic catalysts and involve strongly acidic or oxidizing conditions.…”