Synthesis of 1,3-bis(N,N-difluoroamino)adamantane: addition of difluoramino radicals to 1,3-dehydroadamantane

1,3-Dehydroadamantane undergoes a facile reaction with tetrafluorohydrazine to give 1,3-bis(N,N-difluoroamino)adamantane, the product of 1,3-NF₂ radical addition.     

Condensation of 4-aryl-4-oxobutanoic acids with benzylamines: Synthetic and structural studies on 1-arylmethyl-3-[(<Emphasis Type="Italic">E</Emphasis>)-1-arylmethylidene]-5-phenyl-2,3-dihydro-1H-2-pyrrolones

The microwave-mediated reaction of 4-aryl-4-oxobutanoic acids with benzylamines furnished 1-arylmethyl-3-[(E)-1-arylmethylidene]-5-phenyl-2,3-dihydro-1H-pyrrolones. This result is in contract to the earlier report on this reaction conducted under neat conditions. Structures for the products were assigned on the basis of spectral data and confirmed by independent synthesis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 368–373, March, 2007.     

13C NMR/DFT/GIAO studies of phenylene bis(1,3-dioxolanium) dications and 2,4,6-triphenylene tris(1,3-dioxolanium) trication

The o-, m-, and p-phenylene bis(1,3-dioxolanium) dications (4-6) and 2,4,6-triphenylene tris(1,3-dioxolanium) trication (7) have been prepared by the ionization of the corresponding 2-methoxyethyl benzoates in FSO(3)H or CF(3)SO(3)H at 40 and 60 degrees C, respectively. The charge delocalization in these carbocations was probed by (13)C NMR chemical shifts and substantiated by GIAO/DFT calculations. Relatively less charge is delocalized into the aromatic ring of the carbotrication 7. The rotational barrier around the C(+)-Ar bond for carbodications 4 and 5 was also estimated to be 8-10 kcal/mol.     

Synthesis and characterisation of bis(pentafluorophenyl)antimony(V) cations, [(C6F5)2SbL3]

Pentacoordinate complex cations of the general formula [(C₆F₅)₂SbL₃]³⁺ stabilized as solid salts in combination with tetraphenylborate (BPh₄), tetrafluorobroate (BF₄) anions, where L=DMSO, Ph₃AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required.     

Effect of the rate of diffusion of ions on the periodic precipitation of silver chromate

The effect of the rate of diffusion on the formation ofLiesegang rings of silver chromate in gelatin and agar agar medium has been studied. The rate of diffusion of silver ions in the agar agar gel is much slower than that in gelatin gel during the formation of rings of silver chromate. If the rate of diffusion of silver ions in agar agar gel is increased, even then rings do not form. The only change brought about by the rate of diffusion is for the distance between the successive rings.

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Zusammenfassung Der Einflu\ der Diffusionsgeschwindigkeit auf die Bildung vonLiesegang-Ringen aus Silberchromat in Gelatine und Agar-Agar wurde untersucht. Die Diffusionsgeschwindigkeit der Silberionen in den Agar-Agar-Gelen ist viel niedriger als in den Gelatinegelen während der Bildung der Ringe von Silberchromat. Wenn die Diffusionsgeschwindigkeit der Silberionen in Agar-Agar-Gelen gesteigert wird, bilden sich schlie\lich überhaupt keine Ringe. Der einzige Einflu\, den die Diffusionsgeschwindigkeit hervorruft, ist also änderung des Abstandes aufeinanderfolgender Ringe.

     

Preparation and reactions of mono-reissert compounds and analogs at the 3,4-position of quinazoline

Quinazoline, acid chlorides, and trimethylsilyl cyanide have been converted to mono-Reissert compounds at the 3,4-position of the quinazoline system. Various reactions of these quinazoline Reissert compounds are reported.     

Ruthenium(III) chloride catalyzed acylation of alcohols, phenols, thiols, and amines

Ruthenium(III) chloride catalyzes the acylation of a variety of phenols, alcohols, thiols, and amines under mild conditions. Some of the major advantages of this method are high yields, short reaction times, ease of operation, and compatibility with other protecting groups.     

Molecular composites in thermosets

The synthesis of molecular composites where rigid polymer molecules are reinforcing elements in a thermoset bisimide matrix has been investigated. The approach has been designed to avoid phase separation by selecting systems where reaction of amine-terminated rigid and semiflexible oligomers with maleimide unsaturation occurs prior to crosslinking of the thermoset. This objective has been met for some compositions. The concentration and molecular weight of the rigid oligomers have been varied. The structure of the reinforcing polymer, the reactivity of the maleimide and the conditions for composite synthesis are variables of critical importance, and further work must determine the promise and limitations of this approach.     

A single amino acid Gly-tag enables metal-free protein purification

Analytically pure proteins are indispensable for diverse applications, including therapeutics. Here, we report a methodology where a single amino acid, glycine, enables metal-free protein purification. This robust platform is enabled by a Gly-tag resin for site-specific capture, enrichment, and release through chemically triggered C–C bond dissociation by resonance-assisted electron density polarization.

Gly-tag resin precisely captures and releases a protein with one glycine at the N-terminus. The user-friendly protocol delivers analytically pure protein free of metal contaminants.