Yosef Al Jasem

Wittig- and Horner–Wadsworth–Emmons-olefination reactions with stabilised and semi-stabilised phosphoranes and phosphonates under non-classical conditions

Developments in the Wittig and Horner–Wadsworth–Emmons (HWE)-olefination of aldehydes and ketones with stabilised phosphoranes or phosphonates provide opportunities for multicomponent reactions and for reactions with greatly reduced solvent requirements. The in situ preparation of phosphonium salts, phosphoranes or phosphonates and carrying out the reaction and product workup in a biphasic medium can greatly facilitate the reactions. Microwave irradiation and ultrasonication can shorten reaction times considerably. Wittig and HWE reactions have also been carried out in the solid phase, with either polymer-bound reagents or in Wittig reactions with reagents adsorbed on silica or alumina. Good E- and Z-selectivity has been achieved, despite the E/Z-directivity of the carbonyl reagent and of the residue linked to the phosphorane moiety.

Molecular conformational analysis, vibrational spectra, NBO, NLO, HOMO–LUMO and molecular docking studies of ethyl 3-(E)-(anthracen-9-yl)prop-2-enoate based on density functional theory calculations

FT-IR and FT-Raman spectra of ethyl 3-(E)-(anthracen-9-yl)prop-2-enoate were recorded and analyzed. The conformational behavior of the molecule was also investigated. The vibrational wavenumbers were calculated using DFT quantum chemical calculations. The data obtained from the wavenumber calculations were used to assign vibrational bands obtained experimentally. The geometrical parameters are in agreement with XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis were used to determine the charge transfer within the molecule and quantum chemical parameters related to the title compound. From the MEP analysis, it is clear that the negative electrostatic potential regions are mainly localized over the carbonyl groups and anthracene ring and are possible sites for electrophilic attack and the positive regions are localized at all the hydrogen atoms as possible sites for nucleophilic attack. NLO and NMR studies are also reported. Molecular docking studies suggest that the title compound might exhibit inhibitory activity against IDE and may act as an insulysin inhibitor. Conformational analysis is also reported.

Two ways of preparing benzonitriles using BrCCl 3 –PPh 3 as the reagent

Benzamides were converted into benzonitriles with BrCCl3–PPh3–Et3N in CH2Cl2 in an Appel-type reaction. Benzaldoximes could be transformed to benzonitriles under identical conditions. It was found that the reaction system BrCCl3–(2 equiv.)PPh3 was also suitable for these transformations with PPh3 replacing Et3N.

(E)-Methyl 3-(10-bromo-anthracen-9-yl)acrylate.

In the title molecule, C18H13BrO2, the anthracene unit forms an angle of 46.91 (2)° with the mean plane of the methyl acrylate moiety. In the crystal, the molecules arrange themselves into strands parallel to [010] and, due to the crystal symmetry, there are eight strands crossing the unit cell. In each strand, molecules form short C—H⋯O and C—H⋯π contacts and have their anthracene groups parallel to each other. Neighboring strands, related by a c-glide operation, are connected via C—H⋯O interactions and form a layer parallel to (100). The arrangement of the acrylate and anthracene groups in the crystal do not allow for [2 + 2] or [4 + 4] cycloaddition.

Preparation of 3-(9-Anthryl)acrylates and 9-Aroylethenylanthracenes as Pi-Extended Anthracenes and Their Diels–Alder Type Adducts with Electron-Poor Dienophiles

ABSTRACT (E)-3-(9-Anthryl)acrylates and (E)-9-aroylethenylanthracenes have been prepared by solventless Wittig olefination with conjugated phosphoranes. The (E)-3-(9-anthryl)acrylates were brominated to give (E)-3[10-{9-bromoanthryl}]acrylates, which could be subjected to Suzuki reactions with arylboronic acids to produce (E)-3-[10-{9-arylanthryl}]acrylates as pi-extended systems. The compounds thus prepared were subjected to Diels–Alder reactions, partly under solventless conditions.

Crystal structure of (1Z,2E)-cinnamaldehyde oxime.

The title compound, C9H9NO, crystallized with two independent molecules (A and B) in the asymmetric unit. The conformation of the two molecules differs slightly with the phenyl ring in molecule A, forming a dihedral angle of 15.38 (12)° with the oxime group (O—N=C), compared to the corresponding angle of 26.29 (11)° in molecule B. In the crystal, the A and B molecules are linked head-to-head by O—H⋯N hydrogen bonds, forming –A–B–A–B– zigzag chains along [010]. Within the chains and between neighbouring chains there are C—H⋯π interactions present, forming a three-dimensional structure.

Crystal structure of cholest-5-en-3β-yl 3-(2,4-dimeth-oxy-3-methyl-phen-yl)prop-2-enoate.

In the title compound, C39H58O4, the steroid rings A and C adopt a chair conformation, while ring B adopts a half-chair conformation, and ring D has an envelope conformation, with the methyl-substituted C atom as the flap. In the crystal, molecules pack within layers parallel to (100), with their long axis parallel to the [101] direction. Adjacent layers are linked via C—H⋯O hydrogen bonds and C—H⋯π interactions, forming a three-dimensional framework.

Fluoren-9-one oxime

In the title molecule, C13H9NO, the fluorene system and the oxime group non-H atoms are essentially coplanar, with a maximum deviation from the fluorene mean plane of 0.079 (2) Å for the oxime O atom. A short intramolecular C—H⋯O generates an S(6) ring. In the crystal, molecules related by a twofold screw axis are connected by O—H⋯N hydrogen bonds, forming [100] chains Within these chains, molecules related by a unit translation along [100] show π–π stacking interactions between their fluorene ring systems with an interplanar distance of 3.347 (2) Å. The dihedral angle between the fluorene units of adjacent molecules along the helix is 88.40 (2)°. There is a short C—H⋯π contact between the fluorene groups belonging to neighbouring chains.

Crystal structure of 2-pentyl­oxybenzamide

In the nearly planar 2-pentyloxybenzamide molecule, there is an intramolecular N—H⋯O hydrogen bond involving one amide proton and the ether oxygen. In the crystal, pairs of N—H⋯O hydrogen bonds organize molecules into inversion dimers lying in two planes, (121) and (11).

2,5-Di­meth­oxy­benzo­nitrile

In the title molecule, C9H9NO2, the non-H atoms are essentially coplanar with a maximum deviation of 0.027 (2) Å for the C atom of one of the methyl groups. In the crystal, the molecules are arranged into centrosymmetric pairs via pairs of C—H⋯O and C—H⋯N interactions whereas π–π stacking interactions between the benzene rings [centroid–centroid distance 3.91001 (15) Å] organize them into polymeric strands propagating along the a-axis direction. There is a step of 0.644 (2) Å between the two planar parts of the centrosymmetric pair. In neighboring strands related by the n-glide operation, the aromatic rings are tilted by 29.08 (2)°.