Bruno R. S. de Paula

Crystal structure of (3E)-3-(2,4-di­nitro­phen­oxy­meth­yl)-4-phenyl­but-3-en-2-one

In the title compound, C17H14N2O6, the conformation about the C=C double bond [1.345 (2) Å] is E, with the ketone moiety almost coplanar [C—C—C—C torsion angle = 9.5 (2)°] along with the phenyl ring [C—C—C—C = 5.9 (2)°]. The aromatic rings are almost perpendicular to each other [dihedral angle = 86.66 (7)°]. The 4-nitro moiety is approximately coplanar with the benzene ring to which it is attached [O—N—C—C = 4.2 (2)°], whereas the one in the ortho position is twisted [O—N—C—C = 138.28 (13)°]. The molecules associate via C—H⋯O interactions, involving both O atoms from the 2-nitro group, to form a helical supramolecular chain along [010]. Nitro–nitro N⋯O interactions [2.8461 (19) Å] connect the chains into layers that stack along [001].

Ethyl (2E)-2-(2H-1,3-benzodioxol-5-yl-methyl-idene)-4-chloro-3-oxobutano-ate.

In the title compound, C14H13ClO5, the five-membered ring is in an envelope conformation with the methylene C-atom being the flap. The conformation about the C=C double bond [1.341 (2) Å] is E. The chloropropan-2-one residue is approximately orthogonal to the remaining molecule [dihedral angle = 88.03 (6)°]. In the crystal, the molecules associate via C—H⋯O interactions, involving both carbonyl-O atoms, giving rise to an undulating two-dimensional array in the ac plane.

Crystal structure of 7-[(2E)-2-benzyl­idene-3-oxobut­oxy]-4-methyl-2H-chromen-2-one

Two independent molecules (A and B) comprise the asymmetric unit of the title compound, C21H18O4. There are significant conformational differences between the molecules relating in particular to the relative orientation of the 3-oxo-2-(phenylmethylidene)butoxy substituent with respect to the superimposable chromen-2-one residues. To a first approximation, the substituents are mirror images; both are approximately perpendicular to the chromen-2-one fused ring system with dihedral angles of 88.50 (7) (A) and 81.96 (7)° (B). Another difference between the independent molecules is noted in the dihedral angles between the adjacent phenyl and but-3-en-2-one groups of 8.72 (12) (A) and 27.70 (10)° (B). The conformation about the ethene bond in both molecules is E. The crystal packing features C—H⋯O, C—H⋯π(aryl) and π–π [Cg⋯Cg = 3.6657 (8) and 3.7778 (8) Å] stacking interactions, which generate a three-dimensional network.

Bioreduction of (Z)-3-halo-4-phenyl-3-buten-2-one mediated by Pichia stipitis in ionic liquids

Ionic liquids are substances that are completely composed of ions and are liquid at or close to room temperature. 1 Biocatalysis in ionic liquids media was first reported in 2000. In our studies towards the synthesis of chiral halohydrins using [bmim(BF4)] (water-miscible) and [bmim(PF6)] (water-immiscible), one of the approaches was the bioreduction of the correspondent α-haloenones mediated by Pichia stipitis, so as to generate two stereogenic centers in the same reaction.