Chiral Br?nsted Acid Catalyzed Dynamic Kinetic Asymmetric Hydroamination of Racemic Allenes and Asymmetric Hydroamination of Dienes
The first highly efficient and practical chiral Br?nsted acid catalyzed dynamic kinetic asymmetric hydroamination (DyKAH) of racemic allenes and asymmetric hydroamination of unactivated dienes with both high E/Z selectivity and enantioselectivity are described herein. The transformation proceeds through a new catalytic asymmetric model involving a highly reactive π-allylic carbocationic intermediate, generated from racemic allenes or dienes through a proton transfer mediated by an activating/directing thiourea group. This method affords expedient access to structurally diverse enantioenriched, potentially bioactive alkenyl-containing aza-heterocycles and bicyclic aza-heterocycles.
Alkylation of deprotonated diphenylacetonitrile (2) with an acetal of chloroacetone followed by acidic hydrolysis and reductive amination of the resulting ketonitrile 12 offered an easy access to the methadone precursor 3. By this pathway the formation of the undesired regioisomer 4 was avoided.
Bracher, Franz,Klein, Katrin,Litz, Thomas
p. 271 - 278
(2007/10/03)
Search for new Ca++ antagonists. Lipophilic oximes and phosphonates
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Bellucci,Teodori,Gualtieri
p. 730 - 744
(2007/10/02)
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