2H-Thiopyran-2-thione sulfine, a compound for converting H2S to HSOH/H2S2 and increasing intracellular sulfane sulfur levels.

Reactive sulfane sulfur species such as persulfides (RSSH) and H2S2 are important redox regulators and closely linked to H2S signaling. However, the study of these species is still challenging due to their instability, high reactivity, and the lack of suitable donors to produce them. Herein we report a unique compound, 2H-thiopyran-2-thione sulfine (TTS), which can specifically convert H2S to HSOH, and then to H2S2 in the presence of excess H2S. Meanwhile, the reaction product 2H-thiopyran-2-thione (TT) can be oxidized to reform TTS by biological oxidants. The reaction mechanism of TTS is studied experimentally and computationally. TTS can be conjugated to proteins to achieve specific delivery, and the combination of TTS and H2S leads to highly efficient protein persulfidation. When TTS is applied in conjunction with established H2S donors, the corresponding donors of H2S2 (or its equivalents) are obtained. Cell-based studies reveal that TTS can effectively increase intracellular sulfane sulfur levels and compensate for certain aspects of sulfide:quinone oxidoreductase (SQR) deficiency. These properties make TTS a conceptually new strategy for the design of donors of reactive sulfane sulfur species.

Controllable Cycloadditions between 2H-(Thio)pyran-2-(thi)ones and Strained Alkynes: A Click-and-Release Strategy for COS/H2S Generation.

In this work, we carried out computational studies to predict the cycloaddition efficiency of strained alkynes with 2H-pyran-2-one and its three sulfur-containing analogues: 2H-pyran-2-thione, 2H-thiopyran-2-one, and 2H-thiopyran-2-thione. It was predicted that the decreased aromaticity of the substrate would yield higher reactivity. Experimental studies confirmed the calculation results, and 2H-pyan-2-thiones were found to be the most reactive substrates. This reaction proceeded effectively in aqueous buffers and in cellular environments. It also produced COS as the byproduct, which could be converted into hydrogen sulfide (H2S) in the presence of carbonate anhydrase. This click-and-release approach may serve as a unique way to deliver COS/H2S to specific locations.