Crystal structure of (3E)-3-[(4-nitro-phen-oxy)-meth-yl]-4-phenyl-but-3-en-2-one.

In the title compound, C17H15NO4, the conformation about the C=C double bond [1.348 (2) Å] is E with the ketone group almost co-planar [C-C-C-C torsion angle = 7.2 (2)°] but the phenyl group twisted away [C-C-C-C = 160.93 (17)°]. The terminal aromatic rings are almost perpendicular to each other [dihedral angle = 81.61 (9)°] giving the mol-ecule an overall U-shape. The crystal packing feature benzene-C-H⋯O(ketone) contacts that lead to supra-molecular helical chains along the b axis. These are connected by π-π inter-actions between benzene and phenyl rings [inter-centroid distance = 3.6648 (14) Å], resulting in the formation of a supra-molecular layer in the bc plane.

Crystal structure of (3E)-3-(2,4-di-nitro-phen-oxy-meth-yl)-4-phenyl-but-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 mol-ecules associate via C-H⋯O inter-actions, involving both O atoms from the 2-nitro group, to form a helical supra-molecular chain along [010]. Nitro-nitro N⋯O inter-actions [2.8461 (19) Å] connect the chains into layers that stack along [001].

Ethyl (2Z)-3-oxo-2-(3,4,5-tri-meth-oxy-benzyl-idene)butano-ate.

In the title compound, C16H20O6, the conformation about the C=C double bond [1.344 (2) Å] is Z. With respect to this bond, the ketone is almost coplanar [C-C-C-O torsion angle = -179.60 (10)°] and the ester is almost perpendicular [C-C-C-O = 78.42 (13)°]. The meth-oxy substituents of the central benzene ring are either almost coplanar [C-C-O-C = 3.54 (15) and 177.70 (9)°] or perpendicular [C-C-O-C = 80.08 12)° for the central substituent]. In the crystal, the three-dimensional architecture features C-H⋯O and π-π [inter-centroid distance = 3.6283 (6) Å] inter-actions.

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

In the title compound, C(14)H(13)ClO(5), the five-membered ring is in an envelope conformation with the methyl-ene C-atom being the flap. The conformation about the C=C double bond [1.341 (2) Å] is E. The chloro-propan-2-one residue is approximately orthogonal to the remaining mol-ecule [dihedral angle = 88.03 (6)°]. In the crystal, the mol-ecules associate via C-H⋯O inter-actions, involving both carbonyl-O atoms, giving rise to an undulating two-dimensional array in the ac plane.

Chemoenzymatic synthesis of alpha-hydroxy-beta-methyl-gamma-hydroxy esters: role of the keto-enol equilibrium to control the stereoselective hydrogenation in a key step.

Alpha-hydroxy-beta-methyl-gamma-hydroxy esters not only are found in many natural products and potent drugs but also are useful intermediates in organic synthesis due to their highly functionalized skeleton that can be further manipulated and applied in the synthesis of many compounds with remarkable biological activities. This work was based on a chemoenzymatic approach to obtain these molecules with three contiguous stereogenic centers in a highly enantio- and diastereoselective way. Two distinct linear routes were proposed in which the key steps in both routes consisted of initial stereocontrolled ketoester bioreduction followed by unsaturated carbonyl bioreduction or reduction with Pd-C. Other key reactions in the synthesis include a Wasserman protocol for chain homologation and a Mannich-type olefination with maintenance of enantiomeric excess for all intermediates during the sequence. Whereas route A gave exclusively the skeleton with 3R,4R,5S configuration (99% ee and 11.5% global yield after 7 steps), route B gave the skeleton with 3R,4R,5S and 3R,4S,5R configurations (dr 1:12, 98% ee and 20% global yield after 5 steps).

Ethyl (E)-2-methoxy-imino-2-(4-nitro-benzo-yl)acetate.

The title mol-ecule, C(12)H(12)N(2)O(6), features an E conformation about the oxime group. The methoxy-imino and ester residues are effectively coplanar with each other (r.m.s. deviation for the nine non-H atoms = 0.127 Å) and almost orthogonal [with dihedral angles of 99.44 (13) and -77.85 (13)°, respectively] to the carbonyl and nitro-phenyl groups which lie to either side of this central plane. The crystal structure is consolidated by C-H⋯O contacts.

(Z)-Ethyl 2-hydroxy-imino-2-(4-nitro-benz-yl)ethanoate.

The title mol-ecule, C(11)H(10)N(2)O(6), has a Z conformation about the C=N bond of the oxime unit. There are significant twists from planarity throughout the mol-ecule, the most significant being between the hydroxy-imino and ester groups which are effectively orthogonal with an N-C-C-O(carbon-yl) torsion angle of 91.4 (2)°. The crystal packing features oxime-benzoyl O-H⋯O contacts that lead to chains along [010] and C-H⋯O interactions also occur.

Probing the mechanism of direct Mannich-type alpha-methylenation of ketoesters via electrospray ionization mass spectrometry.

Reactions promoting direct Mannich-type alpha-methylenation of alpha, beta and gamma-ketoesters have been monitored via electrospray ionization mass and tandem mass spectrometric experiments. Key intermediates of the catalytical cycle of this synthetically useful reaction have been intercepted and characterized. The mechanistic information provided by electrospray ionization mass spectrometry/mass spectrometry (ESI-MS/MS) guided the optimization of reaction conditions, allowing alpha-methyleneketoesters to be prepared in high yields (80-95%) and in high-enough purity for immediate further manipulation.

Microbial production of Propionic and Succinic acid from Sorbitol using Propionibacterium acidipropionici.

Three sequential fermentative batches were carried out with cell recycle in four simultaneously operating bioreactors maintained at pH 6.5, 30°C, and 100 rpm. P. acidipropionici ATCC 4875 was able to produce propionic and succinic acid from sorbitol. The concentration of propionic acid decreased slightly from 39.5 ± 5.2 g L(-1) to 34.4 ± 1.9 g L(-1), and that of succinic acid increased significantly from 6.1 ± 2.1 g L(-1) to 14.8 ± 0.9 g L(-1) through the sequential batches. In addition, a small amount of acetic acid was produced that decreased from 3.3 ± 0.4 g L(-1) to 2.0 ± 0.3 g L(-1) through the batches. The major yield for propionic acid was 0.613 g g(-1) in the first batch and succinic acid it was 0.212 g g(-1) in the third batch. The minor yield of acetic acid was 0.029 g g(-1), in the second and third batches.

Crystal structure of 7-[(2E)-2-benzyl-idene-3-oxobut-oxy]-4-methyl-2H-chromen-2-one.

Two independent mol-ecules (A and B) comprise the asymmetric unit of the title compound, C21H18O4. There are significant conformational differences between the mol-ecules relating in particular to the relative orientation of the 3-oxo-2-(phenyl-methyl-idene)but-oxy 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 mol-ecules 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 mol-ecules is E. The crystal packing features C-H⋯O, C-H⋯π(ar-yl) and π-π [Cg⋯Cg = 3.6657 (8) and 3.7778 (8) Å] stacking inter-actions, which generate a three-dimensional network.

Effect of immobilized cells in calcium alginate beads in alcoholic fermentation.

Saccharomyces cerevisiae cells were immobilized in calcium alginate and chitosan-covered calcium alginate beads and studied in the fermentation of glucose and sucrose for ethanol production. The batch fermentations were carried out in an orbital shaker and assessed by monitoring the concentration of substrate and product with HPLC. Cell immobilization in calcium alginate beads and chitosan-covered calcium alginate beads allowed reuse of the beads in eight sequential fermentation cycles of 10 h each. The final concentration of ethanol using free cells was 40 g L-1 and the yields using glucose and sucrose as carbon sources were 78% and 74.3%, respectively. For immobilized cells in calcium alginate beads, the final ethanol concentration from glucose was 32.9 ± 1.7 g L-1 with a 64.5 ± 3.4% yield, while the final ethanol concentration from sucrose was 33.5 ± 4.6 g L-1 with a 64.5 ± 8.6% yield. For immobilized cells in chitosan-covered calcium alginate beads, the ethanol concentration from glucose was 30.7 ± 1.4 g L-1 with a 61.1 ± 2.8% yield, while the final ethanol concentration from sucrose was 31.8 ± 6.9 g L-1 with a 62.1 ± 12.8% yield. The immobilized cells allowed eight 10 h sequential reuse cycles to be carried out with stable final ethanol concentrations. In addition, there was no need to use antibiotics and no contamination was observed. After the eighth cycle, there was a significant rupture of the beads making them inappropriate for reuse.

Chiral Pharmaceutical Intermediaries Obtained by Reduction of 2-Halo-1-(4-substituted phenyl)-ethanones Mediated by Geotrichum candidum CCT 1205 and Rhodotorula glutinis CCT 2182.

Enantioselective reductions of p-R(1)-C(6)H(4)C(O)CH(2)R(2) (R(1) = Cl, Br, CH(3), OCH(3), NO(2) and R(2) = Br, Cl) mediated by Geotrichum candidum CCT 1205 and Rhodotorula glutinis CCT 2182 afforded the corresponding halohydrins with complementary R and S configurations, respectively, in excellent yield and enantiomeric excesses. The obtained (R)- or (S)-halohydrins are important building blocks in chemical and pharmaceutical industries.