M. A. Pereira

3-(4-Bromobenzyl)-5-(4-fluorobenzylidene)imidazolidine-2,4-dione

The imidazolidinedione and fluorobenzylidene rings in the title compound, C 17 H 12 BrFN 2 O 2 , are coplanar ; the dihedral angle between this plane and the plane of the substituted bromobenzyl ring is 104.9(2)°. The molecules in the crystal are held together by hydrogen bonds and van der Waals interactions.

3-Benzyl-5-(2-fluorobenzylidene)-imidazolidine-2,4-dione

The title compound, C17H13FN2O2 has a dihedral angle of 160.5 (1)° between the fluorobenzylidene and the imidazolidinedione rings with an angle of 109.3 (1)° between the latter ring and the benzyl ring . The molecules are linked by a N—H⋯O hydrogen bond [N⋯O 2.852 (3) A].

rac-4-Meth­oxy-6-phenyl-5,6-dihydro-2-pyrone

In the title compound, C12H12O3, the heterocyclic ring adopts a half-chair conformation. C–H⋯O hydrogen bonds form a three-dimensional network.

Crystal structure of 3β-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]- olean-12-ene, C41H58O2, from Peltastes peltatus

C41H58O2, monoclinic, C121 (no. 5), a = 25.573(3) A, £>= 10.453(1) A, c = 14.159(2) A,/3 = 113.674(8), V = 3466.3 A, Ζ = 4, Rp(F) = 0.069, wR^F) = 0.180, T= 120 K. Source of material The crystals of the 3/H5-phenyl-(2£,4E)-penta-2,4-dienoyloxy]olean-12-ene were obtained by recrystallization from MeOH at room temperature.

Crystal structure of 4-hydroxy-6-propenyl-5,6-dihydro-pyran-2-one, C8H10O3

Abstract C8H10O3, monoclinic, P121/c1 (no. 14), a = 5.1640(2) Å, b = 19.979(1) Å, c = 7.5840(4) Å, β = 104.540(2)°, V = 757.4 Å3, Z = 4, Rgt(F) = 0.049, wRref(F2) = 0.169, T = 293 K.

Crystal structure of ent-(16R,17R)-17-hydroxy-17-methoxykauran-19-oic acid, C21H34O4

C 21 H 34 O 4 , orthorhombic, P2 1 2 1 2 1 (no. 19), a = 8.4324(2) A, b = 10.7639(2) A, c = 21.1593(6) A, V= 1920.5 A 3 , Z= 4, R gt (F) = 0.051, wR ref (F 2 ) = 0.125, T= 293 K.

[1a(1aα,5β,9aα)]-1,1a,4,5,7,8,9,9a-Octahydro-3-hydroxy-1,1,2,5-tetramethyl-7-methylene-6H-cyclopropa[3,4]cyclo­hept[1,2-e]inden-6-one

Interest in the title structure, C20H24O2, lies in the novel cis ring junction between the three- and seven-membered rings. This stereochemical arrangement causes the methylene moiety and the cycloheptane ring to be twisted out of the plane of the aromatic ring. The cyclopropane ring is also twisted out of the plane of the aromatic system. The molecules are linked by an O—H⋯O hydrogen bond [O⋯O 2.741 (3) A].

Emmotin 2 : (2R,3S)-2,6-dihydroxy-3-(1-hydroxy-1-methylethyl)-8-methyl-1,2,3,4-tetrahydronaphthalene-5-carbaldehyde

The cyclohexene ring in the title compound, C 15 H 20 O 4 , adopts a half-chair conformation. The C(11) and O(3) atoms are cis to each other. The molecules are linked through intermolecular hydrogen bonds.