Umpolung of donor–acceptor cyclopropanes <i>via</i> N-heterocyclic carbene organic catalysis
نویسندگان
چکیده
A carbene-catalyzed formal umpolung of donor–acceptor (D–A) cyclopropanes is disclosed with chiral spirocyclic lactones bearing multiple functional groups afforded excellent enantio- and diastereoselectivities.
منابع مشابه
Enantioselective cyclopropanation of enals by oxidative N-heterocyclic carbene catalysis.
Carbene catalysed redox activation of α,β-unsaturated aldehydes is applied for generation of α,β-unsaturated acyl azoliums which undergo cyclopropanation upon reaction with a sulfur ylide and an alcohol to give the corresponding cyclopropanecarboxylic acid esters. With chiral carbenes good to excellent diastereo and enantioselectivities are obtained.
متن کاملN-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis
The interplay between metals and N-heterocyclic carbenes (NHCs) has provided a window of opportunities for the development of novel catalytic strategies within the past few years. The recent successful combination of Brønsted acids with NHCs has added a new dimension to the field of cooperative catalysis, enabling the stereoselective synthesis of functionalized pyrrolidin-2-ones as valuable sca...
متن کاملN-Heterocyclic Carbene-Like Catalysis by a Metal−Organic Framework Material
Metal imidazolates, an important class of constructs in metal−organic framework chemistry, are shown here to be precursors to N-heterocyclic carbene-like catalysts. By using n-butyl lithium to deprotonate tripodal imidazolate framework-1 (TIF-1), N-heterocyclic carbene (NHC) sites can be exposed. These sites are found to be remarkably competent as Brønsted-base-type NHC catalysts. An α,β-unsatu...
متن کاملN-Heterocyclic carbene containing element organic frameworks as heterogeneous organocatalysts.
A bifunctional imidazolium linker was used for the production of highly crosslinked element organic frameworks by Suzuki-coupling with tetrafunctional boronic acids. The resulting porous materials are good heterogeneous organocatalysts in the N-heterocyclic carbene-catalyzed conjugated umpolung of α,β-unsaturated cinnamaldehyde.
متن کاملStannyl cyclopropanes by diastereoselective cyclopropanations with (tributylstannyl)-diazoacetate esters catalyzed by Cu(I) N-heterocyclic carbene.
Catalyzed cyclopropanations of alkenes with Bu3SnC(=N2)CO2R (R = Et, t-Bu) have been achieved in good yield with excellent diastereoselectivity to make stannyl cyclopropanes having two or three stereocenters, one of which is quaternary.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Organic chemistry frontiers
سال: 2021
ISSN: ['2052-4110', '2052-4129']
DOI: https://doi.org/10.1039/d1qo00826a