Efficient and Green Preparation of 2-Amino-4H-chromenes by a Room-Temperature, Na₂CO₃-Catalyzed, Three-Component Reaction of Malononitrile, Benzaldehydes, and Phloroglucinol or Resorcinol in Aqueous Medium

<div><p></p><p>The preparation of substituted 2-amino-4H-chromenes by a Na₂CO₃-catalyzed reaction of malononitrile, benzaldehydes, and phloroglucinol or resorcinol in aqueous medium and at room temperature is reported. The merits of this procedure include limited use of organic solvents, easy workup technique, and high purity of products. The 2-amino-4H-chromenes were prepared in yields of 54–96%.</p></div

Fast and efficient synthesis of flavanones from cinnamic acids

<p>A fast and efficient synthesis of flavanones from cinnamic acids in three steps has been developed. First, the cinnamic acid was converted to cinnamyol chlorides using SOCl₂. The acid chlorides were then treated with substituted phenols in BF₃ · OEt₂ to furnish corresponding chalcones in 42(75% yields. Base-catalyzed cyclization of the chalcones at room temperature afforded corresponding flavones in 85–95% yields. The conversion of the cinnamic acid derivatives to corresponding chalcones was found to be sensitive to the position and nature of the substituents on the aromatic rings.</p