132102-76-2Relevant articles and documents
Methoxide-Catalyzed Decomposition of Diarylmethyl (Arylsulfonyl)methyl Sulfoxides: A Sulfine-Forming Elimination on the (E1cB)rev/(E1cB)irrev Borderline
Kice, John L.,Kupczyk-Subotkowska, Lidia
, p. 1424 - 1430 (2007/10/02)
In 7:3 CH3OH-DMSO (v/v) in the presence of methoxide ion, diarylmethyl (arylsulfonyl)methyl sulfoxides (Ar2CHS(O)CH2SO2Ar') 4, undergo elimination remarkably easily to afford the diarylsulfine and the aryl methyl sulfone (eq 4).Comparison of the rate of cleavage of 4 (kelim) and the rate of disappearance of the 1H NMR signal (kCHSO) for the Ar2CHS(O) proton in CD3OD-DMSO shows that the mechanism for the elimination is on the (E1cB)rev/(E1cB)irrev borderline, (kCHSO/kelim) ranging from 1.2 to 5.2, depending on the nature of the Ar and Ar'groups in 4.Slight changes in structure can shift the mechanism from (E1cB)rev to (E1cB)irrev as a result of their effect on the partitioning of the α-sulfinyl carbanion intermediate (Ar2CS(O)CH2SO2Ar') 5, between cleavage to diarylsulfine plus ArSO2CH2- (step kii, eq 8) and protonation to regenerate 4 (step k-i).Structural changes that make Ar'SO2CH2 a better leaving group increase kii/k-i and shift the mechanism toward (E1cb)irrev as does also an increase in the percentage of DMSO in the solvent.Structural changes in Ar that enhance the stability of 5 decrease kii/k-i and shift the mechanism toward (E1cb)rev.It is also shown that for 4 in general kii appears larger than would be expected for a leaving group of the basicity of Ar'SO2CH2-.Repulsion between the dipoles of the S(O) and SO2 groups in 5 is thought to be responsible.
