The title compound, C14H14O4, was synthesized by O-acylation of umbelliferone
with isovaleryl chloride in the presence of diethyl ether as a solvent and pyridine
as a base. The side chain moiety i.e. the acetate fragment linking to the
methylethyl group is almost orthogonal to the almost planar (r.m.s deviation =
0.020 A ˚ ) coumarin ring system, making an angle of 76.26 (7). In the crystal, the
molecules form centrosymmetric dimers through pairwise C—H  O hydrogen
bonds, generating R2
2(8) and R2 2 (18) loops that lie within the crystallographic ac
plane and propagate along the [001] direction.

crystal structure, coumarin derivative, umbelliferone, hydrogen bonds