Synthesis and crystal structure of 5,7-diallyloxy-4-methylcoumarin

The title compound, 5,7-diallyloxy-4-methyl-2H-[1]-benzopyran-2-one, (C₁₆H₁₆O₄), was prepared by condensation of ethyl acetoacetate with phloroglucinol followed by allylation of the 5,7-dihydroxy-4-methylcoumarin thus obtained. The compound crystallizes into monoclinic space group P2₁/c with unit cell parameters a = 7.531(1) Å, b = 22.596(4) Å, c = 8.090(1) Å, β = 92.74(2)°, Z = 4. The crystal structure was solved by direct methods using single crystal X-ray diffraction data and refined to R = 0.0596 for 2166 observed reflections. The coumarin moiety is perfectly planar, with dihedral angle between the two fused rings of 0.46(5)°. The two allyloxy groups have different behaviour, one of them being disordered. Molecules form chains of weak C–H$\cdots$O and C–H$\cdots$π hydrogen bonds.