Assisted cleavage thiols

This suggests that the attack of the thiolate anion, at least with this product, occurs principally on the 3-position of the furoxan ring. An alternative mechanism to that discussed above was proposed to explain NO-donation by this product. It implies the preliminary cleavage of the 1-2 bond of the furoxan ring, rather than of the 2-3 bond as suggested by Feelisch, to give a tertiary nitroso intermediate. Reasonable mechanisms may be put forward to explain the production of different NO-redox forms from this intermediate [20] (Scheme 6.9). Interestingly, some furoxans, such as 31 and related compounds, produce NO, detected as nitrite, spontaneously without the assistance of thiols [21]. 

Although many nucleophiles dehalogenate a-halocarbonyl compounds, the most generally used have been halides, especially iodide ion, thiols and other nucleophilic sulfur species, and phosphines. All of these are effective by themselves, but all benefit by addition of an electrophile to the medium to assist cleavage by coordination to the carbonyl (equation 11). 

Xu H, Sun W, Zhu H, Du F, Liu F, Xu Y, He Y (2013) Design of electrochemical detection of thiols based on the cleavage of the disulfide bond coupled with thionine modified gold nanoparticle-assisted amplification. Chem Commun 49 9603-9605... 

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