Chiral Diamidophosphite Research Articles

Diverse “roof shaped” chiral diamidophosphites: palladium coordination and catalytic applications

“Roof shaped” chiral diamidophosphites of various structures and denticities were obtained and tested in Pd-catalyzed asymmetric allylic substitution.

Pd-Catalyzed Regio-, Diastereo-, and Enantioselective [3 + 2] Cycloaddition Reactions: Access to Chiral Cyclopentyl Sulfones.

The palladium-catalyzed [3 + 2] cycloaddition using in situ generated sulfone-TMM species to construct various chiral cyclopentyl sulfones in a highly regio-, diastereo- (dr >15:1), and enantioselective (up to 99% ee) manner is reported. The present strategy can tolerate different types of sulfone-TMM donors and acceptors, and enables the construction of three chiral centers in a single step, specifically with a chiral center bearing the sulfone moiety. The robust chiral diamidophosphite ligand is the key to the reactivity and selectivities of this transformation.

Pd(0)-Catalyzed Diastereo- and Enantioselective Intermolecular Cycloaddition for Rapid Assembly of 2-Acyl-methylenecyclopentanes.

A highly regio-, diastereo-, and enantioselective trimethylenemethane (TMM) cycloaddition reaction for the rapid assembly of 2-acyl-methylenecyclopentane in an atom-economic fashion is described. This intermolecular protocol allows for facile and divergent access to an array of structurally attractive cyclic adducts. The choice of a robust chiral diamidophosphite ligand, developed by our group, proved to be crucial for the success of this transformation.

Palladium-Catalyzed Regio-, Enantio-, and Diastereoselective Asymmetric [3 + 2] Cycloaddition Reactions: Synthesis of Chiral Cyclopentyl Phosphonates

The palladium-catalyzed unified approach using in situ-generated Phospha-TMM species to synthesize a diverse array of chiral organophosphorus containing carbo- and heterocyclic compounds in a highly regio-, diastereo- (>20:1 dr), and enantioselective (>99% ee) fashion is being disclosed. The present protocol reveals the potential of the deprotonative phospha-TMM strategy for the synthesis of challenging five-membered carbo- and heterocycles, especially those with spirocyclic entities and quaternary asymmetric stereocenters. The choice of the robust chiral diamidophosphite ligand proved to be very crucial for the desired reactivity in the present transformation. Furthermore, the synthetic utility of the products is demonstrated by multiple transformations such as reductions, oxidations, and alkylations.

Diamidophosphites from β-hydroxyamides: readily assembled ligands for Pd-catalyzed asymmetric allylic substitution.

Two groups of modular chiral diamidophosphite ligands were easily synthesised from accessible N-Boc-amino alcohols and pseudodipeptides. The reaction of these compounds with [Pd(allyl)Cl]2 in the presence of AgBF4 yielded complexes [Pd(allyl)(L)2]BF4. In addition, metallochelates [Pd(allyl)(L)]BF4 with (S)-methioninol-based P,S-bidentate ligands were prepared. The structures of the novel ligands and complexes were elucidated by means of 2D-NMR and were confirmed by single-crystal X-ray diffraction, as well as by DFT calculations. Asymmetric inducers of this type exhibited high enantioselectivities in the Pd-mediated allylic substitution of (E)-1,3-diphenylallyl ethyl carbonate with CH2(CO2Me)2 (up to 98% ee) and (CH2)4NH (up to 92% ee). Ee values of up to 86% and 73% were obtained in the Pd-catalyzed allylic alkylation of cinnamyl acetate with ethyl 2-oxocyclohexane-1-carboxylate and ethyl 2-oxocyclopentane-1-carboxylate, respectively. The effects of the structural modules, such as the nature of the phosphorus-containing ring or exocyclic substituent, on the catalytic activity and enantioselectivity were investigated.

Novel chiral diamidophosphites for asymmetric metal-catalyzed reactions

Chiral diamidophosphites with 1,3,2-diazaphospholidine cycles were prepared. A study of these chiral inducers showed them to provide up to 97% ee in the Pd-catalyzed allylic alkylation of (E)-1,3-diphenylallyl acetate with dimethyl malonate.

Diamidophosphites with P*-stereocentres and their performance in metal-catalyzed enantioselective reactions

In this mini-review, the application of P*-chiral diamidophosphites in metal-catalyzed asymmetric reactions. These ligands demonstrate moderate to high levels of asymmetric induction in Pd-catalyzed enantioselective allylations of (E)-1,3-diphenylallyl acetate, desymmetrizations of N,N’-ditosyl-meso-cyclopent-4-ene-1,3-diol bis-carbamate, in the asymmetric construction of quaternary carbon stereocenters and Rh-catalyzed hydrogenation of (Z)-methyl 2-acetamido-3-phenylacrylate.

Chiral inducers with (1R,2R)-1,2-diaminocyclohexane core for organo- and metallocatalysis

A P*-chiral diamidophosphite ligand of the 1,3,2-diazaphospholidine series was obtained by direct phosphorylation of N-[(1R,2R)-2-(tert-butoxycarbonylaminocyclohexyl)]-N′-[(1R)-1-(hydroxymethyl)propyl]oxalamide. The use of this ligand made it possible to reach 98% ee in the Pd-catalyzed allylation involving (E)-1,3-diphenylallyl acetate, 81% ee in the allylation of ethyl 2-oxocyclohexane-1-carboxylate with cinnamyl acetate, 78% ee in the Rh-catalyzed hydrogenation of methyl (Z)-2-acetamido-3-phenylacrylate, and 32% ee in the Rh- and Ir-catalyzed hydrosilylation of (E)-N-(4-methoxyphenyl)-1-phenylethan-1-imine with diphenylsilane. The above mentioned oxalamide provides up to 50% ee in the organocatalytic reduction of the same imine.

Palladium-Catalyzed Asymmetric C(sp3 )-H Allylation of 2-Alkylpyridines.

The palladium-catalyzed asymmetric side-chain C(α)-allylation of 2-alkylpyridines, without using an external base, was developed. The high linear selectivities and enantioselectivities were achieved using new chiral diamidophosphite monodentate ligands. Given that the reaction conditions do not require an external base, this catalyst system enabled chemoselective C(α)-allylation of 2-alkylpyridines containing α-carbonyl C-H bonds, which are more acidic than α-pyridyl C-H bonds.

Palladium‐Catalyzed Asymmetric C(sp3)−H Allylation of 2‐Alkylpyridines

AbstractThe palladium‐catalyzed asymmetric side‐chain C(α)‐allylation of 2‐alkylpyridines, without using an external base, was developed. The high linear selectivities and enantioselectivities were achieved using new chiral diamidophosphite monodentate ligands. Given that the reaction conditions do not require an external base, this catalyst system enabled chemoselective C(α)‐allylation of 2‐alkylpyridines containing α‐carbonyl C−H bonds, which are more acidic than α‐pyridyl C−H bonds.

Palladium and rhodium-catalyzed enantioselective reactions mediated by pseudodipeptide-based phosphite-type ligand

P*-Chiral diamidophosphite ligand of a 1,3,2-diazaphopholidine series bearing the exocyclic pseudodipeptide fragment was synthesized. The possibility of its application in the palladium- and rhodium-catalyzed asymmetric transformations was demonstrated. This ligand provided up to 84% ee in the Pd-catalyzed alkylation of (E)-1,3-diphenylallyl acetate with dimethyl malonate, up to 56% ee in amination of this substrate with pyrrolidine, and up to 68% ee in alkylation of cinnamyl acetate with ethyl 2-oxocyclohexane-1-carboxylate. In the Rh-catalyzed hydrogenation of (Z)-methyl 2-acetamido-3-phenylacrylate mediated by this ligand, up to 53% ee was achieved.

First P,P*-bidentate ligands with P*-chiral diamidophosphite and arylphosphine moieties in Pd-catalyzed asymmetric reactions

GRAPHICAL ABSTRACT

An alliance between chiral phosphite-type compounds and porphyrins in asymmetric palladium catalysis

GRAPHICAL ABSTRACT

Synthesis of New Sulfonium Ylides Bearing the Chiral Diazaphospholidine Group as Reagents for Asymmetric Cyclopropanation

ABSTRACTSulfonium ylides derived from chiral N,N'‐substituted (benzyl, isopropyl, neopentyl) phosphonamides were prepared by reacting appropriate chiral diamidophosphites with potassium hydride and chloromethyl methyl sulfide, and then with methyl iodide in the presence AgBF4 to give the corresponding sulfonium salts in high yields. One of them was analyzed by X‐ray crystallography. The salts upon treatment with different bases (LithiumDiisopropylAmine, BuLi, K2CO3) were converted in situ into ylides, which were reacted with activated olefins to produce phosphonocyclopropanes as a mixture of two diastereoisomers with moderate‐to‐high diastereoselectivities.

ChemInform Abstract: Nonsimple Relationships Between the P*‐Chiral Diamidophosphite and the Arylphosphine Moieties in Pd‐Catalyzed Asymmetric Reactions: Combinatorial Approach and P,P*‐Bidentate Phosphine‐Diamidophosphites.

AbstractP‐Mono‐ and P,P‐bidentate ligands are examined as catalysts for a range of asymmetric allylic substitutions as well as the desymmetrization process involved in the cyclization of meso bis‐urethan (VIII).

Efficient Palladium Catalysts Containing Original Imidazolium-Tagged Chiral Diamidophosphite Ligands for Asymmetric Allylic Substitutions in Neat Ionic Liquid

New imidazolium-tagged chiral diamidophosphite ligands, (S,S)-a and (R)-b, derived from (S,S)-N,N′-dibenzyl-1,2-cyclohexanediamine and (R)-N,N′-dimethyl-1,1′-binaphthyl-2,2′-diamine, respectively, and the corresponding palladium allylic complexes of general formula [PdCl(η3-2-Me-C3H4)(κ1P-L)]BF4 (1a,b) and [Pd(η3-2-Me-C3H4)(κ1P-L)2](BF4)3 (2a,b) were synthesized and fully characterized, including the X-ray crystal structure for 1b. These original Pd/L catalytic systems were applied in asymmetric allylic alkylation, amination, and sulfonylation using rac-3-acetoxy-1,3-diphenyl-1-propene as a substrate in neat ionic liquids, [bmim][PF6] and [Pyr][NTf2]. The best results in terms of enantioselectivity were obtained with the catalytic precursor 1b in [Pyr][NTf2]. The catalytic phase containing 1b for the allylic amination could be recycled up to six times without significant loss of asymmetric induction.

Nonsimple relationships between the P∗-chiral diamidophosphite and the arylphosphine moieties in Pd-catalyzed asymmetric reactions: combinatorial approach and P,P∗-bidentate phosphine-diamidophosphites

A small family of P,P∗-bidentate C1-symmetric ligands containing 1,3,2-diazaphospholidine rings with stereogenic phosphorus atoms has been prepared. Palladium catalytic systems with these phosphine-diamidophosphites afforded 95% and 63% ees in asymmetric allylic substitution and desymmetrization processes, respectively. The influence of the nature of both the phosphine and diamidophosphite moieties of these compounds on the enantioselectivity is discussed. The ‘mixed-ligand approach’ in Pd-catalyzed asymmetric allylation with participation of some new P∗-monodentate diamidophosphites and PPh3 is also considered.

ChemInform Abstract: Asymmetric Tsuji—Trost Substitution in 3‐Acetoxy‐1,3‐diphenylpropene under Phase‐Transfer Conditions.

P*-Chiral diamidophosphite ligand-assisted Pd-catalyzed Tsuji–Trost reaction between dimethyl malonate and prochiral 3-acetoxy-1,3-diphenylpropene in organic solvents using potassium carbonate as the base affords the substitution product in quantitative yields and with enantioselectivities up to 99% ee.

Asymmetric Tsuji–Trost substitution in 3-acetoxy-1,3-diphenylpropene under phase-transfer conditions

P*-Chiral diamidophosphite ligand-assisted Pd-catalyzed Tsuji–Trost reaction between dimethyl malonate and prochiral 3-acetoxy-1,3-diphenylpropene in organic solvents using potassium carbonate as the base affords the substitution product in quantitative yields and with enantioselectivities up to 99% ee.

ChemInform Abstract: Asymmetric Allylic Alkylation in Supercritical Carbon Dioxide Using P*‐Chiral Diamidophosphite Ligands.

P*-Chiral diamidophosphite ligands in the Pd-catalyzed allylic alkylation of ( E )-1,3-diphenylallyl acetate in supercritical carbon dioxide provide enantioselectivities up to 90% ee . The catalytic performance is affected greatly by temperature, CO 2 pressures and structure of catalysts.