Persulfides (RSSH) are important reactive sulfur species (RSS) that are intertwined with the biological functions of hydrogen sulfide (H 2 S). The direct study of persulfides is difficult, however, due to their both nucleophilic and electrophilic character, which leads to the generation of an equilibrium of different RSS. To investigate the effects of persulfides directly, especially in biological systems, persulfide donors are needed to generate persulfides in situ.Here, we report the synthesis of esterase-activated perthiocarbonate persulfide donors and investigate the effects of structural modifications on persulfide release. Although steric bulk of the ester did not significantly alter persulfide release kinetics, increased steric bulk of the thiol increased the persulfide release rate. In addition, we found that the steric bulk and identity of the thiol significantly impact persulfide persistence. Further mechanistic investigations into different competing reaction pathways from perthiocarbonates revealed that multiple RSS can be delivered (i.e., H 2 S, COS, or RSSH) depending on the persulfide donor structure and activator identity.

The enzymatic conversion of carbonyl sulfide (COS) to hydrogen sulfide (H2S) by carbonic anhydrase has been used to develop self‐immolating thiocarbamates as COS‐based H2S donors to further elucidate the impact of reactive sulfur species in biology. The high modularity of this approach has provided a library of COS‐based H2S donors that can be activated by specific stimuli. A common limitation, however, is that many such donors result in the formation of an electrophilic quinone methide byproduct during donor activation. As a mild alternative, we demonstrate here that dithiasuccinoyl groups can function as COS/H2S donor motifs, and that these groups release two equivalents of COS/H2S and uncage an amine payload under physiologically relevant conditions. Additionally, we demonstrate that COS/H2S release from this donor motif can be altered by electronic modulation and alkyl substitution. These insights are further supported by DFT investigations, which reveal that aryl and alkyl thiocarbamates release COS with significantly different activation energies.

<p>The enzymatic conversion of carbonyl sulfide (COS) to hydrogen sulfide (H₂S) by carbonic anhydrase has been used to develop self-immolating thiocarbamates as COS-based H₂S donors to further elucidate the impact of reactive sulfur species in biology. The high modularity of this approach has provided a library of COS-based H₂S donors that can be activated by specific stimuli. A common limitation, however, is that many such donors result in the intermediate formation of an electrophilic quinone methide byproduct during donor activation. As a mild alternative, we demonstrate here that dithiasuccinoyl groups can function as COS/H₂S donor motifs and that these groups release two equivalents of COS/H₂S and uncage an amine payload under physiologically relevant conditions. Additionally, we demonstrate that COS/H₂S release from this donor motif can be altered by electronic modulation and alkyl substitution. These insights are further supported by DFT investigations, which reveal that aryl and alkyl thiocarbamates release COS with significantly different activation energies.</p>

The thiol‐mediated reduction of dithiasuccinoyl groups was harnessed to develop a method for controlled carbonyl sulfide (COS) generation under buffered aqueous conditions. This reactivity generates two equivalents of COS and does not result in formation of electrophilic byproducts such as (imino)quinone methides. The rate of COS generation can be tuned as function of amine identity, and theoretical investigations provide key insights into COS release from thiocarbamate intermediates. For more information, see the Full Paper by M. D. Pluth and co‐workers on page 5374 ff.

The enzymatic conversiono fc arbonyl sulfide (COS) to hydrogen sulfide (H 2 S) by carbonic anhydrase has been used to develops elf-immolatingt hiocarbamates as COS-based H 2 Sd onors to furthere lucidatet he impact of reactive sulfur speciesi nb iology.T he highm odularity of this approach has providedalibrary of COS-based H 2 Sd onors that can be activated by specific stimuli.Acommonl imitation, however,i st hat many such donors result in the formation of an electrophilic quinone methide byproduct during donor activation. As am ilda lternative, we demonstrate here that dithiasuccinoyl groups can function as COS/H 2 Sd onor motifs, and that these groups release two equivalents of COS/H 2 Sa nd uncage an amine payload under physiologically relevant conditions. Additionally,w ed emonstrate that COS/H 2 Sr elease from this donorm otif can be altered by electronic modulationa nd alkyl substitution. These insights are further supported by DFT investigations,w hich reveal that aryl and alkyl thiocarbamates releaseC OS with significantly different activation energies.[a] M.[**] Ap revious versiono ft his manuscript has been deposited on ap reprint server (https://doi.org/10.26434/chemrxiv.11356703.v1).Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Figure 4. Potential energy surface for COS release from PhDTS and AlkylDTS compounds. Calculations were performedusing Gaussian 09 at the B3LYP/6-311 ++G(d,p)l evel of theory applying the IEF-PCM water solvation model. MeSH was used as the thiol nucleophile to simplify accessibleprotonation states of non-participating functional groupso nt he thiol nucleophile.