showing 16 related works from this author
Asymmetric diastereodivergent Michael addition of 2-chloromalonate esters to conjugated imines enabled by catalyst metal change
2019
Despite recent progress in asymmetric diastereodivergent reactions leading to products bearing two stereogenic centers, little research has been devoted to processes were a stereogenic center and a double bond are formed. Here, we report the asymmetric diastereodivergent Michael addition of 2-chloromalonate esters to N-tosyl β,γ-unsaturated α-ketimino esters to give chiral α,β-dehydro-α-aminoesters bearing either a Z or E enamine moiety, using pyBOX-metal complexes. Diastereodivergency is achieved by simply changing the metal ion from a trivalent La(III) to a divalent Ca(II) ion, providing the Z or E enamines. Computational studies reveal the crucial role of London interactions between the …
Catalytic Asymmetric Formal [3+2] Cycloaddition of 2-Isocyanatomalonate Esters and Unsaturated Imines: Synthesis of Highly Substituted Chiral γ-Lacta…
2017
[EN] Unlike their isocyano and isothiocyanato analogues, isocyanato esters remain almost unexplored as formal 1,3-dipoles in asymmetric catalytic reactions. The first asymmetric formal [3+2] cycloaddition involving isocyanato esters and electrophilic alkenes is reported. Diisopropyl 2-isocyanatomalonate reacts with a,b-unsaturated N-(o-anisidyl) imines in the presence of a Mg(OTf)2¿BOX complex to give highly substituted chiral pyrrolidinones featuring a conjugate exocyclic double bond with excellent yields and enantiomeric excesses up to 99%. Several transformations of the resulting heterocycles, including the synthesis of a pyroglutamic acid derivative, have been carried out.
Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters
2018
[EN] In this paper, we report the application of chiral complexes of La(III) with pyBOX ligands as Lewis acid catalysts in the conjugate addition of malonic esters to N-tosyl imines derived from ß,gamma-unsaturated alfa-keto esters to give the corresponding chiral alfa,ß-dehydroamino esters. pyBOX complexes with La(III), Yb(III), Sc(III), and In(III) triflates were assessed in this reaction but only La(III) showed good activity and enantioselectivity, while Yb(III) provided the expected product with low yield and stereoselectivity, and the Sc(III) and In(III) complexes were completely inactive. The complex of La(OTf)3 with the diphenyl-pyBOX ligand prepared in situ provided the best results…
ChemInform Abstract: E,Z-Stereodivergent Synthesis of N-Tosyl α,β-Dehydroamino Esters via a Mukaiyama-Michael Addition
2016
The stereodivergent synthesis of N-tosyl α,β-dehydroamino esters via a Mukaiyama–Michael addition is reported. The reaction of silylketene acetals with N-tosylimines derived from β,γ-unsaturated α-keto esters in dichloromethane provided the corresponding (Z)-α,β-dehydroamino esters while the (E)-isomers were obtained when the reaction was carried out in the presence of 10 mol% copper(II) triflate.
ChemInform Abstract: Asymmetric Conjugate Addition of Malonate Esters to α,β-Unsaturated N-Sulfonyl Imines: An Expeditious Route to Chiral δ-Aminoest…
2014
The asymmetric conjugate addition of malonate esters to α,β-unsaturated N-sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 A MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ-aminoesters and piperidones.
Asymmetric Conjugate Addition of Malonate Esters to α,β-UnsaturatedN-Sulfonyl Imines: An Expeditious Route to Chiral δ-Aminoesters and Piperidones
2013
The asymmetric conjugate addition of malonate esters to α,β-unsaturated N-sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 Å MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ-aminoesters and piperidones.
Mg/BOX complexes as efficient catalysts for the enantioselective Michael addition of malonates to β-trifluoromethyl-α,β-unsaturated ketones and their…
2021
Abstract Magnesium (II)-BOX complexes catalyze the enantioselective Michael addition of malonates to β-trifluoromethyl enones and their N-sulfonyl imines to give ketones or (E)-enamines bearing a trifluoromethylated stereogenic center, respectively, with good yields and high enantiomeric excesses. Magnesium complexes proved to be more active and stereoselective than zinc and copper analogues in these reactions.
E,Z-Stereodivergent synthesis of N-tosyl α,β-dehydroamino esters via a Mukaiyama-Michael addition
2016
The stereodivergent synthesis of N-tosyl α,β-dehydroamino esters via a Mukaiyama–Michael addition is reported. The reaction of silylketene acetals with N-tosylimines derived from β,γ-unsaturated α-keto esters in dichloromethane provided the corresponding (Z)-α,β-dehydroamino esters while the (E)-isomers were obtained when the reaction was carried out in the presence of 10 mol% copper(II) triflate.
Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines
2017
[EN] Copper triflate-BOX complexes catalyse the enantioselective conjugate addition of methyl malonate to beta-trifluoromethyl-alpha,beta-unsaturated imines to give the corresponding enamines bearing a trifluoromethylated stereogenic centre with good yields, and diastereo- and enantioselectivities. The usefulness of the method has been shown with the synthesis of optically active beta-trifluoromethyl delta-amino esters and optically active trifluoromethyl piperidones.
CCDC 1544708: Experimental Crystal Structure Determination
2017
Related Article: Miguel Espinosa, Gonzalo Blay, Luz Cardona, M. Carmen Muñoz, José R. Pedro|2017|Chem.-Eur.J.|23|14707|doi:10.1002/chem.201702777
CCDC 1535017: Experimental Crystal Structure Determination
2017
Related Article: Miguel Espinosa, Jorge Herrera, Gonzalo Blay, Luz Cardona, M. Carmen Muñoz, José R. Pedro|2017|Org.Biomol.Chem.|15|3849|doi:10.1039/C7OB00595D
CCDC 1544707: Experimental Crystal Structure Determination
2017
Related Article: Miguel Espinosa, Gonzalo Blay, Luz Cardona, M. Carmen Muñoz, José R. Pedro|2017|Chem.-Eur.J.|23|14707|doi:10.1002/chem.201702777
CCDC 1442206: Experimental Crystal Structure Determination
2016
Related Article: Miguel Espinosa, Andrea García-Ortiz, Gonzalo Blay, Luz Cardona, M. Carmen Muñoz, José R. Pedro|2016|RSC Advances|6|15655|doi:10.1039/C5RA27354D
CCDC 1581116: Experimental Crystal Structure Determination
2018
Related Article: Miguel Espinosa, Gonzalo Blay, Luz Cardona, Isabel Fernández, M. Carmen Muñoz, Jose R. Pedro|2018|J.Coord.Chem.|71|864|doi:10.1080/00958972.2018.1437422
CCDC 1535016: Experimental Crystal Structure Determination
2017
Related Article: Miguel Espinosa, Jorge Herrera, Gonzalo Blay, Luz Cardona, M. Carmen Muñoz, José R. Pedro|2017|Org.Biomol.Chem.|15|3849|doi:10.1039/C7OB00595D
CCDC 1442362: Experimental Crystal Structure Determination
2016
Related Article: Miguel Espinosa, Andrea García-Ortiz, Gonzalo Blay, Luz Cardona, M. Carmen Muñoz, José R. Pedro|2016|RSC Advances|6|15655|doi:10.1039/C5RA27354D