Catalytic asymmetric endo-selective [3+2] cycloaddition reactions of Schiff bases of α-aminophosphonates with olefins using chiral metal amides

Catalytic asymmetric endo-selective [3+2] cycloaddition reactions of Schiff bases of α-aminophosphonates with olefins are described. While the efficient asymmetric synthesis of several phosphonate analogues of proline derivatives is important in bioorganic chemistry, a direct catalytic method to prepare optically active endo [3+2] cycloadducts of α-aminophosphonates with olefins has never been developed. We found for the first time that catalyst systems prepared from Group 11 metal amides with the (R)-FeSulphos ligand were effective for the asymmetric endo-selective [3+2] cycloaddition to afford the desired proline phosphonate analogues in high yields with high endo- and high enantioselectivities.

Stereoselective Ag-Catalyzed 1,3-Dipolar Cycloaddition of Activated Trifluoromethyl-Substituted Azomethine Ylides

A silver-catalyzed 1,3-dipolar cycloaddition of fluorinated azomethine ylides and activated olefins is reported. The reaction offers a straightforward and atom-economical procedure for the preparation of fluorinated pyrrolidines. Broad scope and high levels of diastereoselectivity have been achieved simply by using AgOAc/PPh3 as the catalyst system. The high efficiency of the cycloaddition relies on the presence of a metal-coordinating group on the imine moiety, such as an ester or heteroaryl group. The asymmetric version of the cycloaddition has been developed by using Taniaphos as a chiral ligand.

A DFT kinetic study on 1,3-dipolar cycloaddition reactions in solution

Several popular density functional theory (DFT) methods have been employed to characterize a series of 1,3-dipolar cycloaddition reactions, including the exploration of reaction mechanisms and the calculations of kinetic parameters.

Organocatalytic asymmetric [3+2] cycloaddition of N-2,2,2-trifluoroethylisatin ketimines with 3-alkenyl-5-arylfuran-2(3H)-ones

An asymmetric [3+2] cycloaddition reaction ofN-2,2,2-trifluoroethylisatin ketimines and 3-alkenyl-5-arylfuran-2(3H)-ones was developed with 1 mol% thiourea–tertiary amine.

Ag-catalyzed diastereoselective [6 + 3] cycloaddition of tropone with homoserine lactone-derived azomethine ylides: synthesis of tricyclic spiropiperidines

Ag-catalyzed [6 + 3] cycloaddition of tropone with homoserine lactone derived azomethine ylides has been developed.

Ligand-controlled stereodivergent 1,3-dipolar cycloaddition of azomethine ylides with 3-methyl-4-nitro-5-styrylisoxazoles

An unprecedented Ag(i)-catalyzed ligand-controlled stereodivergent 1,3-dipolar cycloaddition of azomethine ylides with 3-methyl-4-nitro-5-styrylisoxazoles has been developed to afford heterocycles bearing both methylisoxazole and pyrrolidine moieties.

Templated C-C and C-N Bond Formation Facilitated by a Molybdenum(VI) Metal Center

Preparation of molybdenum dioxido complexes with novel iminophenolate ligands bearing pendant secondary amide functionalities led to unprecedented C-C and C-N coupling reactions of two α-iminoamides upon coordination. The diastereoselective cyclization to asymmetric imidazolidines occurs at the metal center in two consecutive steps via a monocoupled intermediate. A meaningful mechanism is proposed on the basis of full characterization of intermediate and final molybdenum-containing products by spectroscopic means and by single-crystal X-ray diffraction analyses. This process constitutes the first example of a diastereoselective self-cyclization of two α-iminoamides.

Ligand-Controlled Diastereoselective 1,3-Dipolar Cycloadditions of Azomethine Ylides with Methacrylonitrile

Copper-catalyzed reactions of glycine ester arylimines and methacrylonitrile provide selective access to either the endo or exo pyrrolidine cycloadducts. DFT calculations have elucidated the origins of ligand-controlled diastereoselectivity.

Biology-oriented synthesis of benzopyrano[3,4-c]pyrrolidines

A natural product inspired synthesis of 6,6,5-tricyclic compounds via a silver(I)-catalyzed formal 1,3-dipolar cycloaddition of coumarins with α-iminoesters was developed. The reaction proceeds in a stepwise reaction course under formation of the trans-substituted diastereomer with respect to the 1,3-dipole and shows a broad substrate scope.

The copper-catalyzed asymmetric construction of a dispiropyrrolidine skeleton via 1,3-dipolar cycloaddition of azomethine ylides to α-alkylidene succinimides

N,O-Ligand/Cu(OAc)₂ catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides to α-alkylidene succinimides is developed, affording dispiropyrrolidines in excellent diastereoselectivities and enantioselectivities.

Cu(i)/TF-BiphamPhos-catalyzed asymmetric Michael addition of cyclic ketimino esters to alkylidene malonates

Cu(i)-catalyzed asymmetric Michael addition of cyclic ketimino esters with alkylidene malonates has been developed for efficient construction of β-branched α-amino acids containing adjacent quaternary and tertiary stereogenic centers in good yields with excellent diastereo-/enantioselectivities.

The asymmetric synthesis of CF3-containing spiro[pyrrolidin-3,2′-oxindole] through the organocatalytic 1,3-dipolar cycloaddition reaction

A new strategy for the construction of optically active 5′-CF₃ spiro[pyrrolidin-3,2′-oxindole] was described by using CF₃CH₂NH₂ as a building block.

Squaramide-catalysed asymmetric cascade aza-Michael/Michael addition reaction for the synthesis of chiral trisubstituted pyrrolidines

A squaramide catalysed aza-Michael/Michael cascade reaction between nitroalkenes and tosylaminomethyl enones or enoates afforded highly functionalized chiral pyrrolidines in good yields (up to 99%) with good diastereoselectivities (up to 91 : 9 dr) and excellent enantioselectivities (up to >99% ee) under mild conditions.

Brønsted acid-promoted [3 + 3] cycloaddition of azomethine ylides with quinone monoimine: a practical method towards dihydrobenzoxazine derivatives

Brønsted acid-promoted [3 + 3] cycloaddition of azomethine ylides with quinone monoimine provided an expedient access to dihydrobenzoxazine derivatives.

P-stereogenic PNP pincer-Pd catalyzed intramolecular hydroamination of amino-1,3-dienes

A new P-stereogenic PNP pincer-Pd complex was readily prepared and was used in the asymmetric intramolecular hydroamination of amino-1,3-dienes, with the desired products being obtained in good yields and with excellent regioselectivities and up to moderate enantioselectivities.

Isoquinolino[4,3,2-de]phenanthridine: synthesis and its use in 1,3-dipolar cycloadditions to form nitrogen-containing polyaromatic hydrocarbons

The synthesis of the novel azomethine ylide, isoquinolino[4,3,2-de]phenanthridine, and its use in 1,3-dipolar cycloaddition with various alkenes and alkynes to form the corresponding fused pyrrolidines and pyrroles is reported.