Efficient Synthesis of Benzo[g]- and Benzo[h]chromene Derivatives by One-Pot Three-Component Condensation of Aromatic Aldehydes with Active Methylene Compounds and Naphthols.
AbstractA simple, efficient and solvent free approach for the Knoevenagel condensation has been developed which involves grinding of active methylene compounds with aromatic aldehydes over basic alumina. Using this solvent free Knoevenagel approach, a facile and efficient synthesis of 3-cyano and 3-carbethoxycoumarins has also been developed, which involves the grinding of 2-hydroxybenzaldehydes with malononitrile or ethylcyanoacetate respectively over basic alumina followed by grinding with p-toluenesulphonic acid (PTSA) in the same mortar.
The one-pot four-component reaction of aromatic aldehydes, malononitrile, 1,3-thiazolidinedione and ethyl glycinate hydrochloride in ethanol in the presence of triethylamine afforded trans-dihydrothiophene.
Tandem four-component reaction for efficient synthesis of dihydrothiophene with substituted amino acid ethyl esters