• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1379-1384
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• 2004

Rearrangements of 1,3-oxathiolane sulfoxides 8 and 9 in the presence of base are described from a mechanistic viewpoint of sigmatropic and elimination reactions. In the presence of triethylamine the (Z)-sulfoxide 8 gave the corresponding thiolsulfinate 10 by way of dimerization of the sulfenic acid intermediate 2 at room temperature while the (E)-sulfoxide 9 was recovered even after refluxing in ethyl acetate by the reversal of the [2,3]-sigmatropic rearrangement of the sulfenic acid 4. Triethylamine promoted the developing charge separation in the transition state of the sigmatropic rearrangement of the (Z)-sulfoxide 8 to facilitate the ring opening to the sulfenic acid 2. The reason for more facile ring opening of the (Z)-sulfoxide 8 in comparison with the corresponding (E)-sulfoxide 9 is attributable to the differences in the reactivity of the hydrogen adjacent to the carbonyl group. Triethylamine was not strong base to deprotonate the carbonyl-activated methylene hydrogen of the (E)-sulfoxide 9 but enough to catalyze the sigmatropic process of the sulfoxides. The sulfenic acid 2 dimerized to the thiolsulfinate 10 while the sulfenic acid 4 proceeded the sigmatropic ring closure. In the presence of strong base such as potassium hydroxide, the elimination reaction was predominant over the sigmatropic rearrangement. In this reaction condition, both sulfoxides 8a and 9a gave a mixture of the disulfide 12, the isomeric disulfide 14, and the sulfinic acid 13. Under the strong alkaline condition an elimination of activated hydrogen from the carbon adjacent to the carbonyl group to furnish the sulfenic acid 2a and the isomeric sulfenic acid 18. The formation of the transient intermediate in the reaction was proven by isolation of the isomeric disulfide 14. The reactive entity was regarded as the sulfenic acid rather than sulfenate anion under these reaction conditions.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3477-3479
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• 2011

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2521-2522
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• 2009

• Journal of Veterinary Clinics
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• v.18 no.3
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• pp.195-200
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• 2001

Metabolism and phamacokinetics of albendazole have been studied in Korean native cattle after oral administration of 5 mg/kg of albendazole. As ABZ is known to be rapidly biotransformed to many metabolites in most animal species, it is very imperative to establish the analytical conditions for its metabolites. LC/MS methods for ABZSO and ABZS $O_2$met every requirement enough to study the metabolism of pharmacokinetics of albendazole in Korean native cattle. The parent drug (ABZ) was only measured at first two time points of 0.5 h and 1h, whereas two metabolites were consistently formed between 0.5 h to 48-72 h post-treatment. Formation kinetics for ABZSO and ABZS $O_2$were similar. Time to peak concentration (Tmax) of ABZ-SO appeared at 12h post-treatment of ABZ, faster than that of ABZS $O_2$at 24h. Cmax of ABZS $O_2$(1.05$\pm$0.05 ug/ml) was 1.09 times higher than that of ABZSO (0.96$\pm$0.15). Elimination half-life of ABZS $O_2$(4.2 h) was much shorter than ABZS $O_2$(7.0h) (p<0.005). ABZSO was detected until 48h post-administration but ABZS $O_2$was measurable even at 72h post-dosing. AU $C_{0longrightarrow{\infty}}$ of ABZSO was smaller than that of ABZS $O_2$. Regimen of ABZ is advised to take into consideration is metabolite profiles, especially that of ABZSO, an active metabolite.