• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1090-1094
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• 1998

Acid-catalyzed benzidine rearrangements of new unsymmetrical diazanes 1-3, prepared from the reduction of corresponding diazenes 4-6, were carried out in ethanolic solutions. The results are as follows; rearrangement of (3-carbomethoxyphenyl)(3-methoxyphenyl)diazane 1 gave 4,4'-diamino-2-carbomethoxy-2'-methoxybiphenyl 12 (p-benzidine type) in 71% and 10-amino-3-methoxyphenanthridin-6(5H)-one 13, 8-amino-3-methoxyphenanthridin-6(5H)-one 14 in 7.1% and 3.4%, respectively. Product 13 and 14 were formed by the condensation reaction of primarily formed o-benzidine and diphenyline type product, respectively. (5-Carbomethoxy-2-chlorophenyl)(4-methoxyphenyl)diazane 2 and (5-carbomethoxy-2-methylphenyl)(4-methoxyphenyl)diazane 3 underwent mainly disproportionations to give fission amines and corresponding diazenes in about 53% and 40% yields, respectively. The results obtained from the rearrangements of diazanes 1-3 indirectly indicated the importance of disproportionations to understand the benzidine rearrangements. The structures of benzidine rearrangement products were determined by usual NMR techniques such as DEPT, 2D H-H COSY, H-C COSY, 2D NOESY, and Gaussian function multiplication.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.678-681
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• 1991

The Wittig-oxy-Cope rearrangements of deprotonated diallyl ether, I, $CH_2={\bar{C}}H-CH-O-CH_2-CH=CH_2$, have been investigated theoretically by the AM1 method. A two step mechanism forming a Wittig product ion, II, $(CH_2=CH)$ $(CH_2=CH-CH_2)$ $CHO^-$, through a radical-pair intermediate was found to provide the most favored reaction pathway in the Wittig rearrangement. The subsequent oxy-Cope rearrangement from species II also involves a two step mechanism through a biradicaloid intermediate. The intramolecular proton transfer in I (to form $CH_2=CH-CH_2-O-{\bar{C}}H-CH=CH_2$) is a higher activation energy barrier process compared to the Wittig and oxy-Cope rearrangements and is considered to be insignificant. These results are in good agreement with the condensed-phase as well as gas-phase experimental results.

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.156-161
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• 1997

Aqueous 6-hydroxyquinoline in the first excited singlet state undergoes protonation to the imine group first in 15 ps, then in the time scale of 40 ps deprotonation from the enol group and finally, however, quickly as in 11 ps electron rearrangement to change into a resonance hybrid structure of quinoid-prevailing forms. Despite the fact that the decay time constant is smaller than the formation time constant, fluorescence from excited protropic zwitterion is observed to assign its maximum at 510 nm. The electron rearrangement is basically an intramolecular charge transfer from the deprotonated oxygen atom to the positively charged iminium ring without any notable change in nuclear geometry, producing a zwitterionic quinoid structure with much a smaller electric dipole moment than the zwitterionic protropic species. This photoproduct formed by consecutive excited state proton and electron transfers shows a smaller dipole moment in S1 than in S0 and a hypsochromic shift although its S1 state has (π, π*) character.

• Archives of Pharmacal Research
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• 제10권1호
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• pp.25-28
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• 1987

(+)-Ketoprofen was obtained form resolution with (S) (+)-2-amino-1-butanol and its absolute configuration was determined to be (S) by chemical correlation with (S) (+)-ethyl hydratropate using Beckmann rearrangement as a key step.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.933-935
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• 2006

• 대한화학회지
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• 제48권4호
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• pp.439-442
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• 2004

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2815-2818
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• 2013

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1645-1650
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• 2007

This paper describes a racemic and stereoselective synthetic route for a novel cyclohexenyl carbocyclic adenine analogue. The required stereochemistry of the target compound was controlled using a stereoselective glycolate Claisen rearrangement followed by α-chelated carbonyl addition. The introduction of 6-chloropurine was achieved using Mitsunobu conditions, and further modifications of the corresponding heterocycle gave the target cyclohexenyl nucleoside.

• 한국세라믹학회지
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• 제34권9호
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• pp.979-985
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• 1997

The three-dimensional particle packing process is simulated using Lahey FORTRAN 90 as a programming language running on a personal computer. Particle clusters constructed with rearrangement which occurs during packing have higher average coordination number and packing density than particle clusters rearranged after packing. Rearranging particles can not completely block other particles from entering pore volume in 3-dimensional packing unlike in 2-dimensional packing. It is found that there is a region of instability where lower packing density results from the destruction of the ordered packing.

• 대한수학회지
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• 제37권6호
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• pp.929-941
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• 2000

We study a parabolic system of chemotaxis introduced by E.F. Keler and L.A. Segel. First, norm behaviors of the blow-up solution are proven. Then some kind of symmetry breaking and the concentration toward the boundary follow when the L$^1$norm of the initial value is less than 8$\pi$. Meanwhile a method of rearrangement is porposed toprove an inequality of Trudinger-Moser's type.