A green and efficient method for the synthesis of homodimeric (β-dicarbonyl) arylmethanes and dihydropyridine from dimedone in water

Abstract

A direct method has been developed for the synthesis of the dihydropyridine ring system by means of Michael reaction. The reaction of dimedone with 1 .0 equiv. of amines in water provides intermediate product, which allowed dihydropyridine derivatives by intramolecular cyclization in various yields. Of particular interest is the use of the water as solvent of reaction and in absence of catalyst. Also these operating conditions protect the environment and economic points of view.

Catalytic Versatility of Novel Sulfonamide Functionalized Magnetic Composites

“…The catalytic experiments were carried out in a glass round-bottom flask submerged in an oil bath at 90 °C, using 0.7 mmol of aldehyde, 1.4 mmol of dimedone (5,5-dimethyl-1,3-cyclohexanedione), and 50 mg of γ-Fe 2 O 3 /SiO 2 −SDA catalyst in 4 mL of water. When the desired reaction temperature was reached, the mixture was stirred magnetically during 2 h. The melting points of the products in Table 3 were in accordance with data from the literature: 195−197 °C (entry 1), 37 231−233 °C (entry 2a), 42 210−214 °C (entry 2b), 42 243−246 °C (entry 2c), 43 229−231 °C (entry 2d), 43 238−240 °C (entry 2e), 42 241−243 °C (entry 2f), 42 218−221 °C (entry 2g), 42 165−168 °C (entry 3a), 43 and 186−187 °C (entry 3b). 43 Alkylation of Toluene.…”