Photosensitized cyclodimerizations of 4-vinylpyridine, 2-vinylpyridine,and 2-vinylquinoline

Irradiations of 4-vinylpyridine and of 2-vinylpyridine in either f-butyl alcohol or benzene, with benzophenone, yielded a single photodimer, which, on the basis of the nmr and mass spectral data, was assigned the trans-head-to-head structure (I). Upon irradiation in either t-butyl alcohol or benzene, in the presence of benzophenone, 2-vinylquinoline gave a single photodimer whose structure and stereochemistry were also determined from the nmr and mass spectral evidence as (V). Irradiation of 2-vinylquinoline in benzene, in the absence of benzophenone, also gave rise to the same photodimer, but, when t-butyl alcohol or methanol was used as a solvent, no dimer formation was observed.     

A novel synthesis of 2-(disubstituted amino)-5(4)phenylimidazoles

The reaction of 1-phenyl-1,2-propanedione with 1,1-disubstituted guanidines in methanol yielded 2-(disubstituted amino)-4-hydroxy-4-methyl-4H-imidazoles (III). Compound III produced 5(4)methylimidazoles by catalytic hydrogenation and 5(4)chloromethylimidazoles (IV) by concentrated hydrochloric acid treatment. Solvolysis of IV in water and alcohols gave 5(4)hydroxymethyl- and 5(4)alkoxymethylimidazoles, respectively.     

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Mathematische Annalen -     

Effect of N‐methyl amide linkage on hydrogen bonding behavior and water transport properties of partially N‐methylated random aromatic copolyamides

The synthesis, conformational preferences, hydrogen bonding behaviors, and membrane properties of new partially N‐methylated random aromatic copolyamides were reported. These copolyamides were prepared by the low temperature polycondensations of isophthaloyl chloride with 3,5‐diaminobenzoic acid, N,N'‐dimethyl‐4,4'‐diaminodiphenyl ether (MDAE), and 4,4'‐diaminodiphenyl ether. The incorporation of the N‐methyl amide linkages into the polymer backbone decreased the contents of the cis conformation in the N‐methyl amide linkages and suppressed the hydrogen bondings among the amide linkages. Furthermore, the surface hydrophilicity of the copolyamides evaluated by water contact angle measurements decreased with increasing the MDAE unit in the polymer backbone. These experimental results indicated that the suppression of the hydrogen bonding and the existence of the tertiary amide linkage in the cis conformation induced the loose packing of the polymer chains. As a result, the incorporation of the N‐methyl amide linkage increased water flux and decreased salt rejection. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3453–3462     

Stereospecific Transformations of Chiral Compounds Using Anchimeric Assistance of Arylthio and Arylseleno Group

A new chiral pool method is developed starting from readily available chiral oxiranes, the key step being the substitution reaction through the anchimeric assistance of the arylthio and arylseleno group. The overall transformation is the introduction of nucleopiles into the chiral carbon of the oxiranes with retention of the configuration.     

Prevention of Racemization of the Chiral Carbon in the Episelenonium ION Intermediate: Steric Protection and Electron-Withdrawing Effect

To prevent the racemization of the chiral carbon in the episelenonium ion intermediate bearing an aryl group on the selenium atom, both the bulky substituent(s) on the ortho position(s) of the aryl group and electron-with-drawing substituent(s) in the aryl group are found to play an important role.