Copper-catalyzed asymmetric allylic alkylation of racemic cyclic substrates: Application of dynamic kinetic asymmetric transformation (DYKAT)
The copper-catalyzed asymmetric allylic alkylation (AAA) is of great interest in organic synthesis. This reaction was extensively studied using a broad range of substrates, ligands and organometallic reagents. However, the use of racemic substrates was still limited. Although some processes of kinetic resolution are reported in the literature, no examples of quantitative deracemization are described as is the case for the Pd-catalyzed allylic alkylation. We present here a full account of our investigations through the development of the first example of such a process in copper-catalyzed AAA. High enantioselectivities (up to 99% ee), scope of the reaction and mechanistic considerations are reported herein.
Langlois, Jean-Baptiste,Alexakis, Alexandre
supporting information; experimental part
p. 447 - 457
(2010/06/13)
Reactions of Allylidenephosphoranes with Heterocumulenes,I. - Vinylketenimines
According to their α-substituent the allylidenephosphoranes 4 are converted by isocyanates either via Wittig reaction into the hitherto little known vinylketenimines 7 or by carbamoylation and ring closure into the pyrrolone 5 or the 3-pyridylidenephospho
Capuano, Lilly,Willmes, Arnold
p. 80 - 86
(2007/10/02)
MECHANISM OF FORMATION OF 3,5-DIPHENYLISOXAZOLE IN THE REACTION OF 1,2-DIPHENYLCYCLOPROPANES WITH COPPER NITRATE IN ACETIC ANHYDRIDE
In reaction with copper nitrate in acetic anhydride the stereoisomeric 1,2-diphenylcyclopropanes give 3,5-diphenylisoxazole.Preliminary isomerization of the cyclopropane hydrocarbons to the corresponding propenes does not occur during the reaction.For the
Sychkova, L. D.,Kalinkina, O. L.,Shabarov, Yu. S.
p. 1277 - 1281
(2007/10/02)
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