Stereoretentive and regioselective selenium-catalyzed intermolecular propargylic C-H amination of alkynes.
Chem Sci
; 13(7): 2121-2127, 2022 Feb 16.
Article
em En
| MEDLINE
| ID: mdl-35308840
ABSTRACT
Herein we report an intermolecular propargylic C-H amination of alkynes. This reaction is operationally convenient and requires no transition metal catalysts or additives. Terminal, silyl, and internal alkynes bearing a wide range of functional groups can be aminated in high yields. The regioselectivity of amination for unsymmetrical internal alkynes is strongly influenced by substitution pattern (tertiary > secondary > primary) and by relatively remote heteroatomic substituents. We demonstrate that amination of alkynes bearing α-stereocenters occurs with retention of configuration at the newly-formed C-N bond. Competition experiments between alkynes, kinetic isotope effects, and DFT calculations are performed to confirm the mechanistic hypothesis that initial ene reaction of a selenium bis(imide) species is the rate- and product-determining step. This ene reaction has a transition state that results in substantial partial positive charge development at the carbon atom closer to the amination position. Inductive and/or hyperconjugative stabilization or destabilization of this positive charge explains the observed regioselectivities.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Chem Sci
Ano de publicação:
2022
Tipo de documento:
Article