SEARCH Articles Figures Tables Carboxylic acids reactions Coumarin 3,4-dihydro-4-[ Coumarin reactions Coumarin-3-carboxylic acid Coumarin-3-carboxylic acid Knoevenagel reaction Coumarin-3-carboxylic acid, 3,4-dihydro-3-substitutedesters Coumarine-3-carboxylic acid Coumarins Knoevenagel reaction Dihydro reactions Knoevenagel reaction Knoevenagel reaction acidity