Organosulfur compounds serve as pivotal synthons for bioactive molecules, pharmaceutical agents, and functional materials, making the efficient and highly selective construction of C—S bonds a central focus in organic synthesis. However, existing anti-Markovnikov hydrothiolation methods for alkenes suffer from limitations such as reliance on expensive metal catalysts, harsh reaction conditions, poor aqueous phase compatibility, and the need for inert gas protection, hindering their green and large-scale applications. Herein, we report a novel and environmentally benign strategy for the anti- Markovnikov hydrothiolation of alkenes in aqueous phase, using tetrabutylammonium acetate (ⁿBu₄NOAc) as the optimal phase-transfer catalyst (PTC). The reaction proceeds efficiently at room temperature under ambient air, requiring no metals, bases, or inert gas shielding, and achieves a high yield of 85% for the model reaction between atropic acid and p-methoxythiophenol. Catalyst screening confirms the superiority of ⁿBu₄NOAc over other PTCs (e.g., ⁿBu₄NBF₄, TEBAC), with negligible product formation in the absence of a PTC. This method exhibits excellent substrate scope: various substituted thiophenols (electron-donating, electron-withdrawing, halogenated, ortho-substituted, and polyhalogenated derivatives) react smoothly with alkenes, affording desired products in good to excellent yields (up to 98%) while retaining halogen substituents for downstream derivatization. Alkenes including atropic acid esters, heteroaromatic alkenes, and substituted styrenes are also compatible, with electronic effects being the primary factor influencing yields. Gram-scale reaction (5 mmol) delivers a 75% yield (1.08 g), demonstrating promising industrial potential. Additionally, the resulting thioethers can be efficiently oxidized to sulfoxides (85% yield) and sulfones (89% yield) using m-chloroperoxybenzoic acid (m-CPBA). Mechanistic studies suggest dual catalytic pathways: hydrogen bond induction by acetate anions and nucleophilic addition via thiolate anions generated through ion exchange, with ⁿBu₄NOAc playing a dual role. This protocol combines mild conditions, operational simplicity, environmental friendliness, and broad applicability, providing a green and practical alternative for C—S bond construction and advancing sustainable organic synthesis.

Key words: anti-Markovnikov hydrothiolation, C—S synthesis, green chemistry, click chemistry, phase transfer catalysis