- Reactions of Vinyl Sulfoxides with Magnesium Amides. One-Pot Synthesis of Symmetrical and Unsymmetrical β-(Dialkylamino) Dithioacetals
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Vinyl sulfoxides (PhSOCR1=CHR2: R1 = H, Me, or Ph; R2 = H or Me) were treated with (dialkylamino)magnesium reagents, generated in situ from the reaction of EtMgBr with secondary amines (R3R4NH: R3 = Et, i-Pr, or Bn; R4 = Me, Et, or i-Pr) in refluxing Et2O for 1 h, and stirring at room-temperature overnight gave the corresponding symmetrical β-(dialkylamino) dithioacetals [(PhS)2CR1CHR2NR3R4] in 24-84% yields. When the (diethylamino)magnesium reagent was treated with appropriate thiols (RSH; R = p-ClC6H4 or Bn) prior to the interaction with phenyl vinyl sulfoxide, the corresponding unsymmetrical β-(diethylamino) dithioacetals [(PhS)(RS)CHCH2NEt2] were produced in 63-67% yields.
- Kawakita, Masataka,Yokota, Kouichi,Akamatsu, Hideki,Irisawa, Susumu,Morikawa, Osamu,Konishi, Hisatoshi,Kobayashi, Kazuhiro
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- Asymmetric approaches to cyclopentenones in the Ni(0)-promoted cyclocarbonylation reaction of allyl halides and acetylenes
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Different approaches to the asymmetric synthesis of cyclopentenones by means of the Ni(CO)4-promoted alkyne-allyl halide cyclization-carbonylation are reported. The use of acetylenic sulfoxides 1 has proved effective for the synthesis of acyclic, fused [5+8], and spiro [5+5], [5+7], and [5+8] cyclopentenones, whereas placement of the aryl sulfoxide on the allylic system failed to afford any cycloadduct. Homochiral fused [5+8], and spiro [5+7] and [5+8] cyclopentenones have been obtained by this methodology. Finally, a modest enantioselectivity was observed when different homochiral α-substituted carboxylates were used as ligands in our reaction system.
- Villar, Juan Manuel,Delgado, Antonio,Llebaria, Amadeu,Moreto, Josep M.,Molins, Elies,Miravitlles, Carles
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p. 10525 - 10546
(2007/10/03)
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