Enantioconvergent Synthesis of Functionalized γ-Butyrolactones via (3 + 2)-Annulation
نویسندگان
چکیده
A dynamic kinetic resolution of β-halo α-keto esters in an asymmetric homoenolate reaction is described. A chiral N-hetereocyclic carbene catalyzes the a(3) → d(3)-umpolung addition of α,β-enals to racemic α-keto esters, forming γ-butyrolactones with three contiguous stereocenters. The addition occurs with high regio-, diastereo-, and enantiocontrol. This methodology constitutes an intermolecular DKR process to set three stereocenters during the key bond forming event.
منابع مشابه
Correction to “Enantioconvergent Synthesis of Functionalized γ-Butyrolactones via (3 + 2)-Annulation”
Supporting Information. Some of the catalyst identifiers (A−G) used in the Supporting Information did not match those shown in the Communication. We have updated the Supporting Information to eliminate this discrepancy. Prof. D. E. Ward (University of Saskatchewan) alerted us to several relevant publications involving enantioconvergent proline-catalyzed aldol reactions of chiral racemic electro...
متن کاملSynthesis of 2-aryl-3-(2-cyanoethyl)aziridines and their chemical and enzymatic hydrolysis towards γ-lactams and γ-lactones.
Trans- and cis-2-aryl-3-(2-cyanoethyl)aziridines, prepared via alkylation of the corresponding 2-aryl-3-(tosyloxymethyl)aziridines with the sodium salt of trimethylsilylacetonitrile, were transformed into variable mixtures of 4-[aryl(alkylamino)methyl]butyrolactones and 5-[aryl(hydroxy)methyl]pyrrolidin-2-ones via KOH-mediated hydrolysis of the cyano group, followed by ring expansion. In additi...
متن کاملHighly diastereo- and enantioselective NHC-catalyzed [3+2] annulation of enals and isatins.
The chiral N-heterocyclic carbene bearing a proximal hydroxy group derived from L-pyroglutamic acid was found to be an efficient catalyst for the [3+2] annulation of enals and isatins to give the corresponding spirocyclic oxindolo-γ-butyrolactones in good yield with good diastereo- and enantioselectivities.
متن کاملConvenient synthesis of α,β-unsaturated γ-butyrolactones and γ-butyrolactams via decarboxylative iodination of paraconic acids and β-carboxyl-γ-butyrolactams using 1,3-diiodo-5,5-dimethylhydantoin.
A convenient synthetic approach to α,β-unsaturated γ-butyrolactones and α,β-unsaturated γ-butyrolactams is developed. The reaction proceeds via decarboxylative iodination of paraconic acids and β-carboxyl-γ-butyrolactams, employing 1,3-diiodo-5,5-dimethylhydantoin (DIH) under irradiation, followed by dehydroiodination of β-iodo-γ-butyrolactones and γ-butyrolactams providing good yields of α,β-u...
متن کاملA synthesis of γ-trifluoromethyl α,β-unsaturated γ-butyrolactones using CF(3)SiMe(3) as a trifluoromethylating agent.
A general synthesis of γ-trifluoromethyl α,β-unsaturated γ-butyrolactones is described. The fluoride-catalyzed nucleophilic addition of a trifluoromethyl (CF3) group generated from (trifluoromethyl)trimethylsilane (CF3SiMe3, Ruppert-Prakash reagent) to a masked maleic anhydride 1 (cyclopentadiene-maleic anhydride adduct) provides the corresponding adducts 2 with high stereoselectivity. The γ-tr...
متن کامل