When the reaction of thiol with IBX (1.0 equiv) in MeCN was conducted at rt, after 24h, both disulfide 3d and thiosulfonate 2d were isolated in 18 and 75% yields, respectively (entry 4, Table ). Hence, with a longer reaction time of 24h than the previous report of 2h, the in situ generated disulfides can be further oxidized into thiosulfonates (entries 8 vs 4). IBX was then employed in an excess amount to facilitate the oxidation and to reduce the reaction time. To our delight, with 2.0 equiv of IBX in a mixture of solvents, i.e., t-BuOH:H2O or MeCN:H2O, the oxidation of p-methoxythiophenol (1d) led to the corresponding thiosulfonate 2d selectively in respectable isolated yields (entries 12, Table ). When the same reaction was performed in MeCN with 2.0 equiv of IBX, the reaction was over in 12h and the yield of the corresponding thiosulfonate 2d was increased to 91% (entries 3 vs 4). When 3.0 equiv of IBX was employed, the product was isolated in a similar yield (entry 5), and no over-oxidation products were isolated from the reaction. As discussed earlier, with 1.0 equiv of IBX, the yield of thiosulfonate 2d was decreased to 75% (entry 4). It clearly indicates that the reaction required more than 1.0 equiv of oxidant for the complete conversion of thiol 1d to thiosulfonates 2d. Although the reaction worked in other solvents like DCE and DCM, it took a longer duration for completion (entries 67). Thus, the reaction conditions with 1d (0.71 mmol) and IBX (2.0 equiv) in MeCN (10 mL) were considered as the best (Table , entry 3), and it was further implemented to access thiosulfonates from thiols. After optimizations of the reaction with both DMP and IBX, the scope of the methodology was investigated with various substituted thiols 1ak, Scheme 1. The oxidation with DMP occurred in a facile manner for both electron-rich (1a and 1ce) and electron-deficient (1b) thiophenols, where the thiosulfonates 2ae were obtained in 8189% isolated yields. When ortho-substituted thiols 1fh were employed, the oxidation was found to be slower, where the desired products 2fh were obtained in relatively lower yields (7279%). Furthermore, in the case of sterically-hindered 2,4,6-trimethylthiophenol (1j), oxidation using DMP led to an intractable mixture, where isolation of the desired product 2j was not possible. For 3,4-dichlorothiophenol (1i), the corresponding thiosulfonate 2i was isolated in 80% yield. The oxidation of aliphatic thiol, namely, 2-phenylethan-ethiol (1k), with DMP was found to proceed more sluggishly, yielding the corresponding thiosulfonate 2k in only 56% yield. The same series of thiols 1ak was then subjected to oxidation with IBX in MeCN, Scheme 1. Thiophenols 1ae with electron-donating and electron-withdrawing substituent, produced the thiosulfonates 2ae in excellent yields (8591%) within 1236h, Scheme 1a. However, the reaction rates for thiols (1g and 1h) containing electron-withdrawing and ortho-substituents were slower, where the thiosulfonates (2g and 2h) were obtained in lower yields. Specifically, the reactions of sterically-encumbered thiols were sluggish; while the reaction of o-thiocresol (1f) led to the corresponding thiosulfonate 2f in 73% yield, 2,4,6-trimethylthiophenol (1j) yielded the corresponding thiosulfonate 2j in an isolated yield of only 20%. When an aliphatic thiol, namely, 2-phenylethanethiol (1k), was subjected to the reaction condition, the corresponding thiosulfonate 2k was obtained in 79% yield after 48h, Scheme 1b. It is worth mentioning that, the oxidation of electron-deficient p-nitrothiophenol to thiosulfonate was neither feasible with IBX nor DMP.