On the mechanism of hydrolysis of sulfinate esters: oxygen isotope exchange and theoretical studies

Okuyama, Tadashi; Nagase, Shigeru

doi:10.1039/p29940001011

Cited by 6 publications

(4 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, we considered the consequences of thiol attack on the S1 sulfur of the 1,2-dithiolan-3-one 1-oxide ( R1 , Scheme ). This reaction follows an S N 2 mechanism as seen previously for other systems involving nucleophilic attack at sulfinyl sulfur. , The transition state ( TS3 ) is quite early, with a S1−S Nu distance of 3.9 Å and a WBI of 0.03 for the S1−S Nu bond. The reaction has a moderate barrier (9.6 kcal/mol) and is thermodynamically favored by 2.4 kcal/mol.…”

Section: Resultsmentioning

confidence: 52%

Activation of Leinamycin by Thiols: A Theoretical Study

Breydo

Gates

2002

J. Org. Chem.

View full text Add to dashboard Cite

Reaction of thiols with the 1,2-dithiolan-3-one 1-oxide heterocycle found in leinamycin (1) results in the conversion of this antitumor antibiotic to a DNA-alkylating episulfonium ion (5). While the products formed in this reaction have been rationalized by a mechanism involving initial attack of thiol on the central sulfenyl sulfur (S2') of the 1,2-dithiolan-3-one 1-oxide ring, the carbonyl carbon (C3') and the sulfinyl sulfur (S1') of this heterocycle are also expected to be electrophilic. Therefore, it is important to consider whether nucleophilic attack of thiol at these sites might contribute either to destruction of the antibiotic or conversion to its episulfonium ion form. To address this question, we have used computational methods to examine the attack of methyl thiolate on each of the three electrophilic centers in a simple analogue of the 1,2-dithiolan-3-one 1-oxide heterocycle found in leinamycin. Calculations were performed at the MP2/6-311+G(3df,p)//B3LYP/6-31G level of theory with inclusion of solvent effects. The results indicate that the most reasonable mechanism for thiol-mediated activation of leinamycin involves initial attack of thiolate at the S2'-position of the antibiotic's 1,2-dithiolan-3-one 1-oxide heterocycle, followed by conversion to the 1,2-oxathiolan-5-one intermediate (3).

show abstract

Section: Resultsmentioning

confidence: 52%

Activation of Leinamycin by Thiols: A Theoretical Study

Breydo

Gates

2002

J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…[3][4][5] These reactions are well known to proceed through a stepwise mechanism with a hypervalent sulfur species(sulfuranide) as an intermediate or through a single step with synchronous bond formation and breaking (S N 2 type mechanism) as shown in Scheme 1.The tool of criterion for the mechanism of nucleophilic substitution reactions has been most frequently used Bronsted and Hammett eq. For example, a break or curvature in Bronsted plot has often been observed for the aminolysis of ester with good leaving group.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Aminolysis of 4-Nitrobenzenesulfenyl Chloride

Lee¹,

Lee²,

Koo³

2011

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

Nucleophilic substitution reactions at a dicoordinated sulfur compound take place through a bimolecular mechanism 1,2 as well as a tricoordinated sulfur compound. [3][4][5] These reactions are well known to proceed through a stepwise mechanism with a hypervalent sulfur species(sulfuranide) as an intermediate or through a single step with synchronous bond formation and breaking (S N 2 type mechanism) as shown in Scheme 1.The tool of criterion for the mechanism of nucleophilic substitution reactions has been most frequently used Bronsted and Hammett eq. For example, a break or curvature in Bronsted plot has often been observed for the aminolysis of ester with good leaving group. 6,7 Nonlinear free energy relationships have been often interperated as a change of a rate determining step for a stepwise mechanism, while a linear Bronsted plot suggests no change in mechanism.The studies on nucleophilic substitution reactions of a dicoordinated sulfur compound are very rare in comparison with those of a tricoordinated or tetracoordinated sulfur compounds. The authors have performed the kinetic studies on the reaction of 4-nitrobenzenesulfenyl chloride with substituted (X)benzylamines in DMSO at 25 o C to gain further information into the aminolysis mechanism of a dicoordinated sulfur compound. Results and DiscussionThe reaction of 4-nitrobenzenesulfenyl chloride with benzylamines in DMSO obeyed pseudo-first order kinetics under large excess amine concentration. Pseudo-first-order rate constant (k obsd ) was obtained from the slope of the plot of ln(λ−λ t ) vs time and listed in Table 1.The k obsd value increases with increasing concentration of amine, but it shows the upward curvature at higher concentration of amine as shown in Figure 1. Therefore, the k obsd can be given by Eq. (1), where k o is the solvolytic rate constant, and k 2 , k 3 are the second order and the third order rate constants with X-benzylamine, respectively. When the reactions take place as described in Eq. (1), involving the term of general base catalysis, the plot of(2), should be linear, and the expected linear plot was obtained as seen in Figure 2. • ■ Scheme 1

show abstract

“…1-2 For example, the acid hydrolysis of alkyl sulfinate esters as well as cyclic sulfinates proceeds in a concerted SN2 type mechanism, [3][4] while the base catalyzed hydrolysis of cyclic sulfinates with a phenolic leaving group takes place through a hypervalent intermediate. 5 However, there is little report on the aminolysis of sulfinate esters.…”

mentioning

confidence: 99%