A Novel Chemoselective Reaction of Aldehydes with 2‐Mercaptoethanol Catalyzed by SiO₂‐NaHSO₄ under Solvent‐free Condition

Abstract

An efficient and user-friendly procedure has been developed for the chemoselective protection of aldehyde carbonyl groups such as bis(2-hydroxyethyl)dithioacetals with 2-mercaptoethanol catalyzed by silica-supported sodium bisulphate under solvent-free conditions. It has been shown that a variety of aldehydes can expeditiously undergo this reaction to produce their corresponding dithioacetals with impressive yields at room temperature.

Chemistry and application of 4-oxo-4H-1-benzopyran-3-carboxaldehyde

“…An efficient and solvent free synthesis of ChrCH(OAc) 2 and its deprotection to ChrCHO catalyzed by reusable Envirocat EPZ10R under microwave irradiation has been claimed by Shindalkar et al 20 Conversion of ChrCHO into ChrCH(SCH 2 CH 2 OH) 2 with mercaptoethanol is catalyzed by silica supported sodium sulphate under solvent free condition. 21 Indium trifluoride catalyzed protection of the aldehyde group of ChrCHO with MeOH, PhCH 2 OH, 2,2-dimethylpropane-1,3-diol, PhSH, HSCH 2 CH 2 SH, HSCH 2 CH 2 CH 2 SH in refluxing toluene is known. 22 Acetal as well as thioacetal of ChrCHO when refluxed in MeCN-…”

SiO2-NaHSO4 as an Efficient Reusable Heterogeneous Catalyst for the One-Pot Three-Component Synthesis of Octahydro-quinazolin-2,5-diones in Water

“…SiO 2 -NaHSO 4 catalyst was prepared by the reported method [18]. Silica gel (15 g, 100-200 mesh) was added to a magnetically stirred solution of NaHSO 4 .H 2 O (6.9 g, 50 mmol) in distilled water (100 ml) at 25 °C over a 30 min period.…”

“…A literature survey revealed that the use of SiO 2 -NaHSO 4 for the synthesis of xanthenediones [19], ȕ-enaminones, and 2-methylquinolin-4(1H)-ones [20]. Furthermore, SiO 2 -NaHSO 4 has been used in the protection of aldehydes with 2-mercaptoethanol [18]. In a continuation of our work into the synthesis of biologically active heterocyclic compounds using readily available, inexpensive, and environment friendly catalysts [21][22][23][24][25][26], herein we are report the synthesis of octahydro-quinazolin-2,5-diones by the one-pot multi-component reaction of aromatic aldehydes, dimedone, and urea using SiO 2 -NaHSO 4 as an efficient catalyst in water.…”

“…In a continuation of our work into the synthesis of biologically active heterocyclic compounds using readily available, inexpensive, and environment friendly catalysts [21][22][23][24][25][26], herein we are report the synthesis of octahydro-quinazolin-2,5-diones by the one-pot multi-component reaction of aromatic aldehydes, dimedone, and urea using SiO 2 -NaHSO 4 as an efficient catalyst in water. We have found that SiO 2 -NaHSO 4 catalyzes the reaction between aromatic aldehydes, dimedone, and urea in an aqueous medium efficiently to afford the desired products in excellent yield within 1-2 h. The catalyst can be easily prepared [18] and safely handled, making the method more advantageous over other conventional methods and catalysts.…”

Synthesis of High Refractive Spiroheterocyclic Derivatives Through Thioacetalization of Multi-Carbonyl Compounds

“…1 The carbonyl protection using SH often competes with nucleophilic reactions 2 and SH group is sensitive to the oxidation by dimerization and S-oxide formation.…”