• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1588-1592
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• 2009

Lithium cyanoaluminum hydride (LCAH) was prepared by the metal cation exchange reaction of sodium cyanoaluminum hydride with lithium chloride in tetrahydrofuran. The reducing characteristics of LCAH were explored systematically by the reaction with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0 ${^{\circ}C}$). The reducing ability of LCAH was also compared with of the sodium derivative, sodium cyanoaluminum hydride (SCAH). Generally, the reducing behavior of LCAH resembles that of SCAH closely, but the reactivity of LCAH toward representative organic functional groups appeared to be stronger than that of SCAH. Thus, the regent reduces carbonyl compounds, epoxides, amides, nitriles, disulfides, carboxylic acids and their acyl derivatives to the corresponding alcohols or amines, at a relatively faster rate than that of SCAH. The cyano substitution, a strong election-withdrawing group, diminishes the reducing power of the parent metal aluminum hydrides and hence effects the alteration of their reducing characteristics.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.743-749
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• 1993

The approximate rates and stoichiometry of the reaction of excess lithium tris(dihexylamino)aluminum hydride(LTDHA) with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0$^{\circ}$C) were studied in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTDHA was also compared with those of the parent lithium aluminum hydride(LAH), lithium tris(diethylamino)aluminum hydride(LTDEA), and lithium tris(dibutylamino)aluminum hydride(LTDBA). In general, the reactivity toward organic functionalities is in order of $LAH{\gg}LTDEA{\geq}LTDBA>LTDHA$. LTDHA shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, epoxides, and tertiary amides readily. Anthraquinone is cleanly reduced to 9,10-dihydro-9,10-anthracenediol without hydrogen evolution, whereas p-benzoquinone in inert to LTDHA. In addition to that, disulfides are also readily reduced to thiols without hydrogen evolution. However, carboxylic acids, anhydrides, nitriles, and primary amides are reduced slowly. Especially, this reagent reduces aromatic nitriles to the corresponding aldehydes in good yields.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.612-617
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• 1991

The approximate rates and stoichiometry of the reaction of excess 1,3,2-biphenyldioxaborepin [2,2'-biphenoxyborane (BPB)] with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, hydride to compound being 4 : 1, room temperature) was examined in order to define the characteristics of the reagent for selective reductions and compare its reducing power with those of other substituted boranes. The results indicate that BPB is unique and the reducing power is much stronger than that of other dialkoxyboranes, such as catecholborane and di-s-butoxyborane. BPB reduces aldehydes, ketones, quinones, lactones, tertiary amides, and sulfoxides readily. Carboxylic acids, anhydrides, esters, and nitriles are also reduced slowly. However, the reactions of acid chlorides, epoxides, primary amides, nitro compounds, and disulfides with this reagent proceed only sluggishly.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.644-649
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• 1991

The approximate rates and stoichiometry of the reaction of excess lithium tris(dibutylamino)aluminum hydride (LT-DBA) with selected organic compounds containing representative functional groups under standardized conditions (tetrahydrofuran, $0^{\circ}C$) were studied in order to characterize the reducing characteristics of the reagent for selective reductions. The reducing ability of LTDBA was also compared with those of the parent lithium aluminum hydride and the alkoxy derivatives. The reagent appears to be much milder than the parent reagent, but stronger than lithium tri-t-butoxyaluminohydride in reducing strength. LTDBA shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, acid chlorides, epoxides, and amides readily. In addition to that, ${\alpha},{\beta}$-unsaturated aldehyde is reduced to ${\alpha},{\beta}$-unsaturated alcohol. Quinones are reduced to the corresponding diols without evolution of hydrogen. Tertiary amides and aromatic nitriles are converted to aldehydes with a limiting amount of LTDBA. Finally, disulfides and sulfoxides are readily reduced to thiols and sulfides, respectively, without hydrogen evolution.

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.644-649
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• 1994

The approximate rates and stoichiometry of reaction of excess dipyrrolinoaluminum hydride (DPAH) with selected organic compounds containing representative functional groups under standardized conditions (tetrahydrofuran, 0, reagent : compound=4 : 1) were examined in order to define the characteristics of the reagent for selective reductions. The reducing ability of DPAH was also compared with that of bis(diethylamino)aluminum hydride (BEAH). The reagent appears to be stronger than BEAH, but weaker than the parent reagent in reducing strength. DPAH shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, acid chlorides, epoxides, and nitriles readily. In addition to that, ${\alpha},\;{\beta}$-unsaturated aldehyde is reduced to the saturated alcohol. Quinone are reduced cleanly to the corresponding 1,4-reduction products. The examination for possibility of achieving a partial reduction to aldehydes was also performed. Both primary and tertiary aromatic carboxamides are converted to aldehydes with a limiting amount of DPAH. Finally, disulfides and sulfoxides are readily reduced to thiols and sulfides, respectively.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2004.11a
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• pp.150-157
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• 2004

Cruciferous vegetables are rich in organosulfur compounds such as isothiocyanates and sulfides. While the isothiocyanates, corresponding to pungent principle, are generated from myrosinase-catalyzed hydrolysis of glucosinolates, the sulfides can be generated non-enzymatically. Recent studies provide evidences that some sulfur compounds in these vegetables show a chemopreventive action against carcinogenesis; while isothiocyanates such as sulforaphane induce phase 2 enzymes (glutathione S-transferase/quinone reductase), disulfides tends to elevate the level of phase 1 and 2 enzymes. Especially, sulforaphane rich in Cruciferae vegetables has been reported to express anticarcinogenic effect in some organs such as liver, kidney or intestine. When the level of sulfur compounds in Cruciferous and Alliaceous vegetables was determined by GC/MS (SIM), the richest in sulforaphane is broccoli followed by turnip, cabbage, radish, kale, cauliflower and Chinese cabbage. Meanwhile, the sulfides are predominant in Alliaceous vegetables such as onion. In related study, the administration of vegetable extract elevated the GST level by 1.5 fold for broccoli, 1.4 fold for radish, and 1.3 for onion. Thus, the vegetables frequently used in Korean dish contain relatively high amount of anticarcinogenic sulfur compounds. Moreover, the combination of broccoli and radish extracts elevated the GST induction up to 1.84 folds of control. In addition, the Kakdugi, fermented radish Kimchi was observed to show a comparable GST induction despite the decomposition of methylthio-3-butenylisothiocyanate (MTBI). Therefore, the combination of vegetables including broccoli, and fermented radish Kimchi would be useful as a functional food for chemoprevention.

• Applied Biological Chemistry
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• v.51 no.3
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• pp.183-187
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• 2008

Alkyl thiosulfi(o)nates, analogs of allyl-2-propene-1-thiosulfinate isolated from Allium sativum and having antibacterial activity, were chemically synthesized and their biological activities were investigated. Alkyl thiosulfinates were prepared by oxidation of corresponding disulfides with organic peroxy acid, while alkyl thiosulfonates could be obtained by oxidation of the alkyl thiosulfinates using sodium periodate. All synthetic thiosulfi(o)nates showed antibacterial activity against Staphylococcus aureus B33 and antifungal activity against Candida utilis ATCC42416. Further more synthetic alkyl thiosulfonates displayed antioxidant activity and have also prevention effect of platelet aggregation induced by collagen in rat.

• Journal of the Korean Chemical Society
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• v.41 no.3
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• pp.130-137
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• 1997

Powders and thin-layers of a hexagonal titanium disulfide phase have been successfully prepared by modifying the sol-gel process. The reaction of titanium isopropoxide with hydrogen sulfide causes the precipitation of a precursor which was converted to the disulfide on heat-treatment in $H_2S$ at various temperatures depending on the solvent adopted, whereas that of titanium 2-methoxyethoxide with $H_2S$ produces a stable solution which was spin-casted onto silicon substrates followed by thermolysis to give thin films. Upon heat-treatment in $H_2S$, the disulfides show interesting morphological variations in the form of their powders and thin films, which were characterized by SEM and X-ray diffractometer.

• Korean journal of food and cookery science
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• v.28 no.2
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• pp.143-148
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• 2012

$Dumebuchu$ ($Allium$ $senescens$ L. var. $senescens$) has a peculiar and long-lasting odor that resembles the flavor of garlic and onions. This study was conducted to examine the volatile compounds of essential oils extracted from $dumebuchu$. The essential oils of $dumebuchu$ were extracted by hydrodistillation using a clavenger-type apparatus and analyzed by GC-MS. A total of 25 compounds were identified in the essential oils from $dumebuchu$. Among sulfur-containing compounds, 4 disulfides and 3 trisulfides were identified. The most abundant sulfur-containing compound was 5-dimethylthiophene (peak area 41.15%) and the second and the third most abundant compound were dipropyl disulfide (18.91%) and propyl allyl disulfide (12.23%), respectively.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.890-895
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• 1997

The approximate rates and stoichiometry of the reaction of excess lithium tripiperidinoaluminum hydride (LTPDA), an alicyclic aminoaluminum hydride, with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 25°) were examined in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTPDA was also compared with those of the parent lithium aluminum hydride (LAH) and lithium tris(diethylamino)aluminum hydride (LTDEA), a representative aliphatic aminoaluminum hydride. In general, the reactivity of LTPDA toward organic functionalities is weaker than LTDEA and much weaker than LAH. LTPDA shows a unique reducing characteristics. Thus, benzyl alcohol, phenol and thiols evolve a quantitative amount of hydrogen rapidly. The rate of hydrogen evolution of primary, secondary and tertiary alcohols is distinctive. LTPDA reduces aldehydes, ketones, esters, acid chlorides and epoxides readily to the corresponding alcohols. Quinones, such as p-benzoquinone and anthraquinone, are reduced to the corresponding diols without hydrogen evolution. Tertiary amides and nitriles are also reduced readily to the corresponding amines. The reagent reduces nitro compounds and azobenzene to the amine stages. Disulfides are reduced to thiols, and sulfoxides and sulfones are converted to sulfides. Additionally, the reagent appears to be a good partial reducing agent to convert primary carboxamides into the corresponding aldehydes.