• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2025-2028
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• 2014

Anion receptor 1 based on acylhydrazone has been designed and synthesized. UV-vis and $^1H$ NMR titration showed that receptor 1 is selective receptor for dihydrogen phosphate ($H_2PO_4{^-}$). Dihydrogen phosphate was complexed by the receptor 1 via at least 4 hydrogen bonding interactions, contributing from two amide N-Hs and two imine C-Hs. In addition, nitrogen in the aromatic ring could make 2 additional hydrogen bondings with OH groups in the dihydrogen phosphate. However, the receptor 1 could make only 4 hydrogen bonds with halides. Therefore, receptor 1 could bind anions through hydrogen bonds with a selectivity in the order of $H_2PO_4{^-}$ > $Br^-$ > $Cl^-$ in highly polar solvent such as DMSO.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2077-2080
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• 2014

Cobalt-immobilized SBA-15 6a-c was synthesized from alkyne-attached SBA 5a-c by the reaction with $Co_2(CO)_8$ in toluene. Alkyne group was introduced into amino SBA-15 (4) by imine-linkage or substitution with propargyl bromide to afford iminoalkyne 5a and aminoalkyne 5b, respectively. Meanwhile, alkyne 5c was prepared in one-step by reacting triethoxysilyl hexyne with SBA-15. Dicobalt-complexes 6a-c were characterized by means of FT-IR, solid-state NMR and elemental analysis.

• Journal of the Korea Safety Management & Science
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• v.1 no.1
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• pp.259-272
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• 1999

In order to enhance the selectivity, productivity and yield of methyl fructoside, which was synthesized by enzymatic glycosylation of sucrose and methanol solution, controlling of surface property of solid support using different immobilization procedures optimized microenvironment of immobilized invertase. Silanization and polyethylene imine coating methods were adopted to give a hydrophobic and hydrophilic environment of immobilized invertase. As a result, polyethyleneimine coating method gave higher loading of enzyme, effective activity, and relative activity than silanization method, because it brought on increasing the functional density of amino group and enhancing the conservation of activity by regulating of hydrophilicity. And then, hydrophilic environment was possible to restraint the assessing of methyl fructoside molecule, which was more hydrophobic than sucrose, fructose, and glucose molecule in the reaction mixture, into .the active site of immobilizedinvertase. Consequently, hydrophilic microenvironment of immobilized invertase by polyethyleneimine coating obtained higher yield and productivity with increasing conversion than silanized and native invertase. Thus, this procedure optimized the microenvironment of immobilized invertase suitable for the enzymatic synthesis of methyl fructoside.

• Journal of the Korean Chemical Society
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• v.34 no.3
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• pp.297-303
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• 1990

$VO^{2+}-catalyzed oxidation of n-butylamine by hydrogen peroxide shows that the reaction is a first order in the concentration of n-butylamine, acid added, and VO^{2+}$ as catalyst, respectively. The reactions involve the initial formation of an imine intermediate, followed by hydrolysis to butyraldehyde and ammonia. It is suggested that the rate-determining step is a process dehydrogenation of n-butylammine.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.850-858
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• 2010

The electronic absorption spectra of five Schiff bases derived from 2-hydroxy-1-naphthaldehyde with glycine, alanine, leucine, valine and phenylalanine have been measured in various solvents. The observed bands were assigned to the proper electronic transitions and compared with the predicted transitions at the semiempirical level of theory. The calculated equilibrium constants are in agreement with the experimental results, predicting the existence of all studied compounds predominantly or completely in keto-imine tautomerism. On the other hand, a correlation between $\nu\;(cm^{-1})$ (main frequency of each compound) and the well known solvent parameters $E_T$ (30), $\varepsilon_T$, $\pi^*$ been made. Furthermore, the acid dissociation constants, $pK_a$, were determined by using three different spectrophotometric methods.

• YAKHAK HOEJI
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• v.40 no.5
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• pp.507-512
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• 1996

Some allylamine compounds which are benzothiazole substituants in stead of naphthyl ring in naftifine, antifungal agents, were synthesized as potential antimycotics. The interme diate Schiff bases that were obtained by condensation of 2-aminobenzothiazole and trans-cinnamaldehyde, were reduced to imine compounds to give allylamines (5a-5d) after methylation. These compounds which were tested in vitro against five fungal cell lines containing Trichophyton mentagrophytes, showed no activity in 0.1~100${\mu}$g/ml range.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1537-1540
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• 2013

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1037-1042
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• 1995

The reaction of acetophenone 1-ureidoethylidenehydrazones 6 with a mixture of triphenylphosphine, carbon tetrachloride, and triethylamine in dichloromethane provides a general route to 1-(1-phenylethenyl)-5-(N-substituted amino)-1,2,4-triazoles 11 via the electrocyclization of the expected azino carbodiimide intermediates 9 to give the resonance stabilized azomethine imine 10a followed by a proton abstraction from the methyl group by amide anion. However, the same reaction of benzaldehyde 1-ureidoethylidenehydrazones 5 was unsuccessful. Under the same conditions, the reactions of benzaldehyde 1-N-acylureidoethylidenehydrazones 7 or acetophenone 1-N-acylureidoethylidenehydrazones 8 afforded 4H-1,2,4-triazolo[1,5-c][1,3,5]oxadiazines 16 or 17 via the zwitterionic species 15, or a [4+2] intramolecular cycloaddition from the carbodiimide intermediates 14, respectively.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.560-564
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• 1991

The gas-phase pyrolysis reactions of iminoethers (Ⅱ), 2-alkoxypyridines (Ⅲ), 2-N-alkylated pyridones (Ⅳ) and N-alkylated acetamides (Ⅴ) have been studied MO theoretically with the AM1 method. The decomposition of these compounds proceeds by a concerted retro-ene process through a six-membered cyclic transition state. The reactivity decreases in the order (Ⅱ) > (Ⅲ) > (Ⅳ) > (Ⅴ), with a greater reactivity for the imine series, (Ⅱ) and (Ⅲ), compared to the amide series, (Ⅳ) and (Ⅴ), and a difference in basicity between the N and O atoms. Within a given series, however, the reactivity is dictated mainly by the aromaticity in the transition state. The reactivity order with respect to side alkyl chain of a species was found to increase as the steric crowding effect increases. The AM1 reactivity in this work agree well with the experimental results.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.625-630
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• 1995

α-Linked D-altropyranosidic derivatives were obtained by configurational change at C-3 of α-D-mannopyranosides as the key step in preparation of allyl and methyl α-D-glycopyranosides of 6-deoxy-D-altro-heptose. The manno-altro conversion was effected by sequential reactions of Swern oxidation and stereoselective borohydride reduction. Allyl 4,6-O-benzylidene-2-O-p-methoxybenzyl-α-D-mannopyranoside was transformed to the corresponding altropyranoside via 3-oxo-arabino-hexopyranoside. Allyl 7-O-benzyl-6-deoxy-3,4-O-isopropylidene-α-D-altro-heptopyranoside has been prepared as a glycosyl acceptor to be coupled with β-D-GlcpNAc-(1→3)-α-D-Galp glycosyl donor for the synthesis of an O-antigen repeating unit of Campylobacter jejuni serotypes O:23 and O:36. Stereoselective borohydride reduction also succeeded in yielding methyl 2,4,7-tri-O-benzyl-6-deoxy-α-D-altro-heptopyranoside from the corresponding 3-oxo-α-D-arabino-heptopyranoside. C-6 Homologation was achieved by sequential reactions of cyanide displacement of 6-sulphonates, reduction of the resulting heptopyranosidurononitrile with diisobutylaluminum hydride, hydrolysis of the imine, and further reduction with sodium borohydride.