Hahn, HG Nam, Kee Dal Cheon, SH 2024-01-21T06:30:53Z 2024-01-21T06:30:53Z 2021-09-05 2004-09-20 0253-2964 https://pubs.kist.re.kr/handle/201004/137225 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 cave 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. English KOREAN CHEMICAL SOC NUCLEOPHILIC-SUBSTITUTION HYDROLYSIS KINETICS ESTERS SULFUR Base-catalyzed rearrangement of some 1,3-oxathiolane sulfoxides: Mechanistic viewpoint of the sigmatropic and elimination reactions Article 1 BULLETIN OF THE KOREAN CHEMICAL SOCIETY, v.25, no.9, pp.1379 - 1384 BULLETIN OF THE KOREAN CHEMICAL SOCIETY 25 9 1379 1384 scie scopus kci ART000942140 000224290800021 2-s2.0-4644247495 Chemistry, Multidisciplinary Chemistry Article NUCLEOPHILIC-SUBSTITUTION HYDROLYSIS KINETICS ESTERS SULFUR siamatropic rearrangement sulfoxide sulfenic acid thiolsulfinate sulfinic acid