Synthesis of vinyl sulfides via hydrothiolation of alkynes using Al2O3/KF under solvent-free conditions

Synthesis of vinyl sulfides using glycerol as a recyclable solvent

“…Aiming to reduce the reaction time, the mixture in glycerol was irradiated with focused microwaves at the same temperature (90 °C, Method C). It was observed complete consume of thiol 1a after irradiation for 10 min and 3a was obtained in 95% yield (Table 1, 22 The experiments were performed at 60…”

“…22 It was found that the best conditions for the hydrothiolation consists in stirring a mixture of 1a (2 mmol) and 2a (1 mmol) in presence of 0.08g (51 mol%) of KF/Al2O3 (40%) at gently heating (60 ˚C) and under N2 atmosphere, (Table 1, entry 1).…”

“…19 More recently, we have described several efficient approaches using KF/Al2O3. 22,23 As a continuation of our studies we report herein the full results of the hydrothiolation of alkynes 1 using KF/Al2O3 without any solvent (Method A), 22 as well as the use of glycerol as recyclable solvent for this reaction (Scheme 1).…”

“…All microwave tests were conducted using a CEM Discover, mode operating systems working at 2.45 GHz, with a power programmable from 1 to 300 W. General preparation of alumina-supported potassium fluoride. [22][23][24] To a 100 mL beaker was added alumina (6.0 g of Al2O3 90, 0.063-0.200 mm, Merck), KF.2H2O (5.2 g) and water (10 mL). The suspension was stirred for 1 h at 65 °C, dried at 80 °C for 1 h and for an additional 4 h at 300 °C in an oven and then cooled in a desiccator.…”

“…22 To a mixture of appropriate alkyne 1 (2 mmol) and thiol 2 (1 mmol) under N2 atmosphere, KF/Al2O3 (0.08g, obtained as described above) was added at room temperature. Then, the temperature was slowly raised to 60 °C.…”