No abstract

Efficient syntheses of 3,4-dihydropyrimidin-2-(1H)-ones and the corresponding thioxo derivatives using 1,3-dibromo-5,5-dimethylhydantoin (DBH) catalysis of a one-pot three-component Biginelli reaction of aldehydes, ethyl acetoacetate, and urea or thiourea under microwave irradiation are described. The advantages of this method are its short reaction times, high yields of the products, inexpensive and commercially available catalyst, and solvent-free conditions. Typical isolated yields exceed 70 % for arylaldehydes (9 examples) and aliphatic aldehydes (2 examples).

In this research, we have used Fe3O4@nano‐cellulose–OPO3H as magnetic bio‐based nanocatalyst for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones via condensation of 2‐aminobenzamide and different aldehydes. The major advantages of the present methodology are good yields, ecofriendly catalyst, and easy workup.

Zr(HSO 4 ) 4 as a solid acid was applied for the acetalization of carbonyl compounds, at room temperature, under solvent-free conditions with good to excellent yields. The low cost and availability of the reagents, versatile procedure and easy work-up make this method attractive for the organic synthesis of these compounds.

A combination of silica sulfuric acid and potassium chlorate in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of alcohols to their corresponding aldehyde or ketone derivatives in acetonitrile or toluene with good yields.