Enantioselective [4+2] cycloaddition of ketenes and 1-azadienes catalyzed by N-heterocyclic carbenes.
نویسندگان
چکیده
Optically active highly functionalized 3,4-dihydropyridin-2-ones were synthesized by N-heterocyclic carbene-catalyzed [4+2] enantioselective cycloaddition of ketenes and 1-azadienes.
منابع مشابه
Enantioselective [2+2+2] cycloaddition of ketenes and carbon disulfide catalyzed by N-heterocyclic carbenes.
The chiral N-heterocyclic carbene-catalyzed [2+2+2] cycloaddition of ketenes and carbon disulfide was realized to give the cycloadduct of 1,3-oxathian-6-ones in good yields with excellent enantioselectivities.
متن کاملEnantioselective formal [2+2] cycloaddition of ketenes with nitroso compounds catalyzed by N-heterocyclic carbenes.
Chiral N-heterocyclic carbenes were found to be efficient catalysts for the formal [2+2] cycloaddition reaction of alkyl(aryl)ketenes and nitroso compounds to give the corresponding 1,2-oxazetidin-3-ones in moderate to good yields with high enantioselectivities. Reductive ring-opening of the oxazetidinones give the corresponding α-hydroxy acid derivatives in good yields.
متن کاملHighly enantioselective [4 + 2] cyclization of chloroaldehydes and 1-azadienes catalyzed by N-heterocyclic carbenes.
Highly functionalized dihydropyridinones were synthesized via the N-heterocyclic carbene-catalyzed enantioselective [4 + 2] annulation of α-chloroaldehydes and azadienes. Hydrogenation of the resulted dihydropyridinones afforded the corresponding piperidinones with high enantiopurity.
متن کاملN-heterocyclic carbene-catalyzed [4 + 2] cycloaddition of ketenes and 3-aroylcoumarins: highly enantioselective synthesis of dihydrocoumarin-fused dihydropyranones.
The N-heterocyclic carbene-catalyzed [4 + 2] cyclization of ketenes and 3-aroylcoumarins has been developed to give the corresponding dihydrocoumarin-fused multisubstituted dihydropyranones in high yield with good diastereoselectivity and high enantioselectivity.
متن کاملA theoretical study on the reaction mechanisms and stereoselectivities of NHC-catalyzed [2 + 2] cycloaddition of ketene with C=N double bond of isothiocyanate
In this work, three possible mechanisms, including mechanisms A and B associated with the stereoselective [2 + 2] cycloaddition product and mechanism C associated with the [2 + 2 + 2] cycloaddition product, have been investigated for N-heterocyclic carbenes (NHCs) catalyzed cycloadditions of ketenes with isothiocyanates by using density functional theory (DFT). Our calculated results suggest th...
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ورودعنوان ژورنال:
- Chemical communications
دوره 47 8 شماره
صفحات -
تاریخ انتشار 2011