Reactions of Vinyl Sulfoxides with Magnesium Amides. One-Pot Synthesis of Symmetrical and Unsymmetrical beta-(Dialkylamino) Dithioacetals.

Vinyl sulfoxides (PhSOCR(1)=CHR(2): R(1) = H, Me, or Ph; R(2) = H or Me) were treated with (dialkylamino)magnesium reagents, generated in situ from the reaction of EtMgBr with secondary amines (R(3)R(4)NH: R(3) = Et, i-Pr, or Bn; R(4) = Me, Et, or i-Pr) in refluxing Et(2)O for 1 h, and stirring at room-temperature overnight gave the corresponding symmetrical beta-(dialkylamino) dithioacetals [(PhS)(2)CR(1)CHR(2)NR(3)R(4)] in 24-84% yields. When the (diethylamino)magnesium reagent was treated with appropriate thiols (RSH; R = p-ClC(6)H(4) or Bn) prior to the interaction with phenyl vinyl sulfoxide, the corresponding unsymmetrical beta-(diethylamino) dithioacetals [(PhS)(RS)CHCH(2)NEt(2)] were produced in 63-67% yields.