• YAKHAK HOEJI
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• v.28 no.2
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• pp.97-100
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• 1984

We have investigated the feasibility of using cyclic ambident nucleophiles in s-triazine ring transformation reaction and found that they can replace the $N_{1}-C_{2-N_{3}$ fragment of s-triazine directly in basic conditions, yielding the corresponding bicyclic products. In this paper, we described the reaction and mechanistic aspects of s-triazine to pyrimidopyrimidine transformation by 6-aminouracil derivatives. This type of ring transformation is supposed to be first attempt that deals with the successful s-triazine to bicyclic heterocycle transformation.

• YAKHAK HOEJI
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• v.37 no.2
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• pp.113-118
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• 1993

3-Phenyl-5, 6, 7, 8-tetrahydrothiazolo[3, 2-$\alpha$][1, 3]diazepine, which has pharmaceutical activities, was reacted with phenyl isothiocyanate to give 3-phenyl-9-phenyl(thiocarbamoyl)-5, 6, 7, 8-tetrahydrothiazolo[3, 2-$\alpha$][1, 3]diazepi nium-betaine. New biheterocyclic compounds were prepared by the ring transformation reaction of the above reactive betaine with $\alpha$-haloesters and $\alpha$-haloketones such as ethyl bromoacetate, methyl bromoacetate, chloroacetone, and 4'-methoxyphenacyl bromide, respectively. In each ring transformation reaction, two major products supposed to be geometrical isomers were obtained.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.511-514
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• 2002

• YAKHAK HOEJI
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• v.44 no.4
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• pp.325-333
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• 2000

The 1,3-dipolar cycloaddition reaction of the quinoxaline 4-oxides 2 with 2-chloroacrylonitrile gave the 2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxalines 3, which were converted into the 2,3,4,6-tetrahydro-1H-1,2-diazepino[3,4-b]quinoxalines 5-7. The reaction of compounds 3 with selenium dioxide in acetic acid/water resulted in ring transformation to give the 1,4-dihydro-4-oxopyridazino[3,4-b]quinoxalines 8.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.164-166
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• 1988

7-Dithiocarboxy-3-phenyl-5,6-dihydro imidazo[2,1-b]thiazolium-betaine (2) was prepared by treatment of 3-phenyl-5,6-dihydro imidazo[2,1-b]thiazole (1) with carbon disulfide in acetone at room temperature. On the reaction of 2 with para-substituted phenacyl bromides (4) having the electron withdrawing property by virtue of (+) resonance (R) < (-) inductive (I) or (-) resonance (R), (-) inductive (I) effect, ring transformation product p-substituted-2-[2-[7-(p-substituted benzoyl)-5-thioxo-2,3-dihydro-1H-imidazo[1,2-c] thiazol-1-yl]-2-phenylvinylthio] acetophenone (6) was obtained; however, when R is electron donating grops with (+) resonance (R) > (-) inductive (I) effect the quarternary ammonium salt 7-(p-substituted phenyl) carbonyl methyl-3-phenyl-5,6-dihydro imidazo [2,1-b] thiazolium bromide (8) is formed. The reaction of 2 with unsubstituted-phenacyl bromide (R = H), on the other hand, gives 6a and 8a to the similar ratio, respectively.

• Archives of Pharmacal Research
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• v.12 no.1
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• pp.17-21
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• 1989

We have reported earlier on the reactivity of 7-dithiocarboxy-3-phenyl-5,6-dihydro imidazo[2,1-b]thiazolium-betaine with several para-substituted phenacyl bromides. In this work reactions of 7-dithiocarboxy-3-phenyl(or methyl)-5,6-dihydro imidazo[2,1-b]thiazolium-betaine with a series of aliphatic alkylating agents of ${\alpha}$ -halo ketone,${\gamma}$-halo koto ester and ${\alpha}$ -halo ester were examined for the similar purpose. In case of ${\alpha}$-halo ketone or ${\gamma}$-halo koto ester such as ${\alpha}$ -chloro acetone or ethyl 4-chloro acetoacetate new biheterocyclic compound was obtained via ring transformation reaction. However, reaction of the betaine with methyl(or ethyl) bromoacetate used as a ${\alpha}$-halo ester, gave, in-stead, S-alkylated quarternary ammonium salt.

• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.272-276
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• 1985

Various new kinds of biheterocyclic betaines were prepared by the reaction of 3-substituted-6,7-dihydro-5H-thiazolo[3,2-a]pyrimidine with electrophiles such as isothioyanates, isocyanates in aprotic solvents, respectively. The biheterocyclic betaines containing methyl group at 3-position of thiazole ring were obtained particularly in good yields at room temperature. These betaines were also reacted with alkyl halide to give quarternary ammonium salts. It was found that these betaines are dissociated in polar organic solvents depending on temperature. And new biheterocyclic compounds via ring transformation were prepared by the reaction of 8-phenyl (thiocarbamoyl)-3-phenyl-6,7-dihydro-5H-thiazolo[3 ,2-a]pyrimidinium-betaine with ${\alpha}$-halo kester ${\alpha}-halo$ ester and ${\gamma}-halo$ keto ester.

• Journal of the Korean Chemical Society
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• v.41 no.12
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• pp.677-678
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• 1997

• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.318-324
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• 2001

The reaction of 6-chloro-2-hydrazinoquinoxaline(4) or 6-chloro-2-hydrazinoquinoxaline 4-oxide(7) with alkyl (ethoxymethylene)cyanoacetates gave pyrazolylquinoxalines(5, 8). The reaction of compounds 8 with dimethyl acetylenedicarboxylate resulted in the 1,3-dipolar cycloaddition reaction and then ring transformation to afford pyrazolylpyrrolo[1,2-a]quinoxalines(9).

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.323-327
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• 1984

Nicotine was reacted with an equimolar amount of ozone in methylene chloride and distilled water. The reaction mixture was separated by column chromatography or thin layer chromatography and then purified by vacuum distillation. The six compounds obtained from this reaction were characterized by NMR, IR and Mass spectrometry. These were identified as unchanged nicotine, nornicotine, anabasine, ${\beta}$-nicotyrine, cotinine and nicotine-N-oxide. From these results, reaction mechanism for the ozonolysis ofon nicotine was proposed; the pyrrolidine ring is attacked by ozone at the 1'-position followed by further transformation.