Reactions of Sulfoxides with Magnesium Amides. Transformations of Sulfoxides into Sulfides, Dithioacetals and Vinyl Sulfides

Article abstract of DOI:10.1246/bcsj.68.1401

The reactions of sulfoxides with magnesium amides generated in situ from the reaction of ethylmagnesium bromide and seconday amines, such as diisopropylamine (DIPA) or 2,2,6,6-tetramethylpiperidine (TMP) in diethyl ether, were examined.Diaryl sulfoxides were heated with the diisopropylaminomagnesium reagent in diethyl ether to give the corresponding diaryl sulfides in 42-52percent yields.Sulfoxides bearing hydrogens at the α-position only(RSOCH2R¹) reacted with the tetramethylpiperidinomagnesium reagent at room temperature to produce the corresponding dithioacetals (RSCHR¹SR) in 47-86percent yields.The treatment of sulfoxides bearing hydrogens both at the α-and β-positions (RSOCHR¹CHR²R³) with the magnesium amides at room temperature afforded the corresponding vinyl sulfides (RSCR¹=CR²R³) in 52-72percent yields accompanying 2.3-27percent yields of the corresponding dithioacetals.The pathways leading to the products involving the formation of the sulfur-stabilized carbonium ion intermediates are discussed.