1-(Di­bromo­methyl)-4-methoxy-2-methyl­benzene

The title compound, C₉H₁₀Br₂O, is a major product of the radical bromination of 4-methoxy-1,2-di­methyl­benzene. Each Br atom is involved in a close contact with the O atom of a neighbouring mol­ecule, forming a geometry that is suggestive of weak intermolecular OBr charge-transfer interactions.     

The synthesis of R-3-alkoxy-1-(1′-hydroxyethyl)-4-methoxy-2-(1″-propenyl)benzenes utilizing Corey-Bakshi-Shibata asymmetric reductions

Pyrolysis of the 3-O-allyl derivative 7 of isovanillin followed by alkylation of the derived allylphenol 8 afforded a series of benzaldehyde derivatives 9-11 each of which was transformed by initial treatment with methylmagnesium bromide followed by oxidation of the corresponding alcohols with activated manganese dioxide into a series of ketones 15-17. Palladium(0) catalysed isomerization of the double bond in the prop-2′-enyl side-chain afforded ketones 36-38 which were subjected to the Corey-Bakshi-Shibata asymmetric reduction protocol to afford the R-3-alkoxy-1-(1′-hydroxyethyl)-4-methoxy-2-(1″-propenyl) benzenes 42-44 in yields of approximately 60% and with ee's of 75%.     

4-(1-Adamantylamino)-2-amino-6-methoxy-5-nitrosopyrimidine

The title compound, C₁₅H₂₁N₅O₂, lies on a crystallographic mirror plane and is hydrogen bonded to neighbouring mol­ecules by infinite chains formed by combinations of strong N—H⃛N and soft C—H⃛O hydrogen bonds. The pyrimidine moiety shows extensive delocalization.     

Electronic properties of hydrogen-bonded complexes of benzene(HCN)(1-4): comparison with benzene(H2O)(1-4)

The electronic properties, specifically, the dipole and quadrupole moments and the ionization energies of benzene (Bz) and hydrogen cyanide (HCN), and the respective binding energies, of complexes of Bz(HCN)(1-4), have been studied through MP2 and OVGF calculations. The results are compared with the properties of benzene-water complexes, Bz(H(2)O)(1-4), with the purpose of analyzing the electronic properties of microsolvated benzene, with respect to the strength of the CH/π and OH/π hydrogen-bond (H-bond) interactions. The linear HCN chains have the singular ability to interact with the aromatic ring, preserving the symmetry of the latter. A blue shift of the first vertical ionization energies (IEs) of benzene is observed for the linear Bz(HCN)(1-4) clusters, which increases with the length of the chain. NBO analysis indicates that the increase of the IE with the number of HCN molecules is related to a strengthening of the CH/π H-bond, driven by cooperative effects, increasing the acidity of the hydrogen cyanide H atom involved in the π H-bond. The longer HCN chains (n ≥ 3), however, can bend to form CH/N H-bonds with the Bz H atoms. These cyclic structures are found to be slightly more stable than their linear counterparts. For the nonlinear Bz(HCN)(3-4) and Bz(H(2)O)(2-4) complexes, an increase of the binding energy with the number of solvent molecules and a decrease of the IE of benzene, relative to the values for the Bz(HCN) and Bz(H(2)O) complexes, respectively, are observed. Although a strengthening of the CH/π and OH/π H-bonds, with increasing n, also takes place for the Bz(H(2)O)(2-4) and Bz(HCN)(3-4) nonlinear complexes, Bz proton donor, CH/O, and CH/N interactions are at the origin of this decrease. Thus CH/π and OH/π H-bonds lead to higher IEs of Bz, whereas the weaker CH/N and CH/O H-bond interactions have the opposite effect. The present results emphasize the importance of both aromatic XH/π (X = C, O) and CH/X (X = N, O) interactions for understanding the structure and electronic properties of Bz(HCN)(n) and Bz(H(2)O)(n) complexes.