Pd-catalyzed Asymmetric Allylic Amination Research Articles

Axially Chiral N,N-Ligand-Promoted Pd-Catalyzed Enantioselective Allylic Amination and Alkylation.

An axially chiral N,N-ligand developed from a [1,1'-binaphthalene]-2,2'-diol (BINOL)-based skeleton and phenanthroline is found to be capable of promoting Pd-catalyzed asymmetric allylic amination and alkylation of allyl acetates. The reaction is compatible with cyclic and acyclic secondary amines, primary aliphatic amines, malononitrile, and dialkyl malonates, affording the corresponding chiral products in up to 99% yield and with up to >99% enantiomeric excess.

Towards enantiopure macrocyclic trans-dinucleating hemilabile P-Alkene ligands: Syntheses, structures, and Chiral Pd-Complexes

Dibenzazepinyl dichlorophosphine 2 reacts with (R,R)-2,3-O-isopropylidene-threitol (3) in Et2O solution to afford gram-quantities of the enantiopure macrocylic phosphoramidite (all-R)-6, which may be seen as a formal dimer of classic phosphoramidite P-alkene hybrid ligands. Complexation experiments with PdCl2 reveal highly selective formation of the trans-dinuclear complex (all-R)-11. The corresponding bulkier and rigidly trans-eclipsed 1,4-diol (S,S)-bis-hydroximethyl-9,10-dihydro-9,10-ethaneanthracene (4) does not favor macrocycle formation and exclusively leads to the new dibenzazepinyl phsophormaidite P-alkene ligand 7, which in Pd-catalyzed asymmetric allylic amination comes the well-known ‘privileged’ binol-derived P-alkene analogue 1 close in terms of enantioselection.

Synthesis of Chiral α,β-Unsaturated γ-Amino Esters via Pd-Catalyzed Asymmetric Allylic Amination.

A Pd-catalyzed asymmetric allylic amination of 4-substituted 2-acetoxybut-3-enoates with amines has been developed for the regiospecific synthesis of chiral α,β-unsaturated γ-amino esters. The desired chiral aminated products can be obtained in up to 98% yield, and 99% ee and can be conveniently transformed to chiral γ-amino acid/alcohol derivatives and chiral γ-lactams, which can then be subjected to the synthesis of several types of chiral drugs and drug candidates. The preferential formation of chiral γ-amino esters may be attributed to the bulky substituents on the right side of the allyl substrates. This work provides an efficient strategy for the synthesis of chiral α,β-unsaturated γ-amino esters and their derivatives.

Regio- and Stereocontrolled Synthesis of 3-Substituted 1,2-Diazetidines by Asymmetric Allylic Amination of Vinyl Epoxide.

Pd-catalyzed asymmetric allylic amination of rac-vinyl epoxide with unsymmetrical 1,2-hydrazines proceeds with excellent regio- and stereocontrol, which after further ring closure provides differentially protected 3-vinyl-1,2-diazetidines in good yields. The chirality at C-3 exerts stereocontrol over the nitrogen centers in the 1,2-diazetidine with all substituents orientating themselves trans to their neighbors. Efficient functionalization without rupture of the strained ring is demonstrated (e.g., by cross-metathesis), establishing the first general route to C-3-substituted 1,2-diazetidines in enantioenriched form.

ChemInform Abstract: Asymmetric Synthesis of Axially Chiral Anilides by Pd‐Catalyzed Allylic Substitutions with P/Olefin Ligands.

As an attractive class of non-biaryl atropisomeric compounds, C–N axially chiral anilides have received considerable attention, and several methods have been successfully developed for their synthesis. Pd-catalyzed asymmetric allylic amination was proved to be an effective approach for the chiral anilide synthesis, although only moderate enantioselectivity and relatively narrow substrate scope have been achieved in the previous work. Searching for highly efficient methods for the synthesis of axially chiral anilides is therefore of great interest in synthetic and pharmaceutical chemistry. In this paper, a palladium-catalyzed asymmetric allylic substitution of ortho-substituted anilides using phosphorus amidite–olefin ligands was successfully achieved to afford a variety of axially chiral anilides in high yields with up to 84% ee. The absolute configurations of chiral anilides were also determined from X-ray and CD spectra.

Pd-catalyzed asymmetric allylic amination with BOP ligands and its applications to the synthesis of fused polycyclic alkaloids

Pd-catalyzed asymmetric allylic amination reaction of piperonylamides and a 2-siloxymethylcyclohexenyl carbonate, using chiral biphenol-based diphosphinite (BOP) ligands gave the corresponding cyclohexenylpiperonylamides in excellent yield and enantiopurity (93–95% ee). These amides were applied to the synthesis of fused polycyclic alkaloids in a short sequence of steps.

ChemInform Abstract: Enantioselective Synthesis of Planar Chiral Ferrocenes via Pd(0)‐Catalyzed Intramolecular Direct C—H Bond Arylation.

A highly efficient synthesis of planar chiral ferrocenes by enantioselective Pd(0)-catalyzed direct C–H arylation from readily available starting materials under mild reaction conditions was developed (up to 99% yield, 99% ee). The products can be easily transformed to the highly efficient planar ferrocene ligands, which have demonstrated high efficiency in Pd-catalyzed asymmetric allylic alkylation and amination reactions.

Enantioselective Synthesis of Planar Chiral Ferrocenes via Pd(0)-Catalyzed Intramolecular Direct C–H Bond Arylation

A highly efficient synthesis of planar chiral ferrocenes by enantioselective Pd(0)-catalyzed direct C-H arylation from readily available starting materials under mild reaction conditions was developed (up to 99% yield, 99% ee). The products can be easily transformed to the highly efficient planar ferrocene ligands, which have demonstrated high efficiency in Pd-catalyzed asymmetric allylic alkylation and amination reactions.

Palladium/sulfoxide-phosphine-catalyzed highly enantioselective allylic etherification and amination.

The Pd/sulfoxide-phosphine-catalyzed highly enantioselective allylic etherification and amination with a wide range of O- and N-nucleophiles have been developed (up to 97% yield, 98.5% ee). The products can also be conveniently transformed into biologically active chiral heterocycles.

Spiroketal-Based Diphosphine Ligands in Pd-Catalyzed Asymmetric Allylic Amination of Morita–Baylis–Hillman Adducts: Exceptionally High Efficiency and New Mechanism

Exceptionally high activity (with a TON up to 4750) of the palladium complexes of SKP ligand was discovered in the catalysis of asymmetric allylic amination of MBH adducts with aromatic amines. A comprehensive mechanistic study indicates that the unique structural features of the SKP ligand, with a long P···P distance in its solid-state structure, were favorable for allowing two P atoms to play a bifunctional role in the catalysis. Herein, one of the P atom forms a C-P σ-bond with the terminal carbon atom of allyl moiety as a Lewis base, and an alternative P atom coordinates to Pd atom. The cooperative action of organo- and organometallic catalysis discovered in the present catalytic system is most likely responsible for its high activity, as well as excellent regio- and enantioselectivities. The mechanism disclosed in the present catalytic system is distinct from most of the currently recognized mechanisms for Pd-catalyzed allylic substitutions.

The synthesis of chiral β-aryl-α,β-unsaturated amino alcohols via a Pd-catalyzed asymmetric allylic amination

Chiral β-aryl-α,β-unsaturated amino alcohols were synthesized via a Pd-catalyzed asymmetric allylic amination of 4-aryl-1,3-dioxolan-2-one using planar chiral 1,2-disubstituted ferrocene-based phosphinooxazolines as ligands. Under the optimized reaction conditions, a series of substrates were examined and the products were obtained in good to excellent yields (up to 92%) and enantioselectivities (up to 98% ee) under mild reaction conditions. The desired products were determined to be of (R)-configuration and could subsequently be transformed into compounds with interesting biological activity using simple transformations.

Bifunctional Ligand Promoted Pd-Catalyzed Asymmetric Allylic Etherification/Amination

A serious of bissulfoxide-phosphine ligands are examined on the Bronsted basicity of sulfinyl moiety. The effect of secondary binding property of the ligand is demostrated in Pd-catalyzed asymmetric allylic etherification and amination (up to 99% ee). And the application scope of this methodology to hydrogen-donor nucleophiles is investigated.

Regio- and Enantioselective Pd-Catalyzed Allylic Amination of Monosubsti­tuted Allylic Substrates with BocNHOMe

A new type of N-nucleophile has been developed in Pd-catalyzed asymmetric allylic amination with monosubstituted allyl substrates, affording corresponding branched allyl amines in high regio- and enantioselectivities. Either OMe or Boc group in products can be removed easily to provide primary amine derivatives with the optical purity unchanged.

Asymmetric Synthesis of 2-Substituted Hexahydroquinolin-4-ones Using a Pd-Catalyzed Asymmetric Allylic Amination and Intramolecular Mannich Reaction: Catalytic Asymmetric Synthesis of 2-epi-cis-195A

A novel method of the enantioselective synthesis of 2-substitutedhexahydroquinolin-4-ones is described. The method relies on a Pd-catalyzedasymmetric allylic amination using a chiral diaminophosphine oxide(DIAPHOX) preligand and diastereoselective intramolecular Mannichreaction. The developed synthetic method could be applied to thecatalytic asymmetric synthesis of (+)-2- EPI- CIS-195A.

Formal Enantioselective Total Synthesis of Schulzeines A–C via Pd–Catalyzed Intramolecular Asymmetric Allylic Amination

Formal enantioselective total synthesis of schulzeines A-C was accomplished, featuring highly efficient Pd-catalyzed asymmetric allylic amination using novel diphosphonite ligands (BOPs) to provide 1-vinyltetrahydroisoquinoline key intermediates, as well as Ru-catalyzed ring-closing metathesis reaction to construct the key tricyclic cores in enantiopure form with correct absolute configurations.

Synthesis of Novel Bidentate P-Chiral Diaminophosphine Oxide Preligands: Application to Pd-Catalyzed Asymmetric Allylic Substitution Reactions

We developed a novel (S)-L-phenylalanine derived-bidentate chiral diaminophosphine oxide (DIAPHOX) preligand (S,S(P))-9b, which was successfully applied to Pd-catalyzed asymmetric allylic alkylation and amination. Using the Pd-(S,S(P))-9b catalyst system, asymmetric allylic alkylation and amination proceeded very smoothly, affording the corresponding products in excellent yield with high enantiomeric excess. It is noteworthy that both enantiomers were accessible with high enantiomeric purity using the structurally related DIAPHOX preligands (S,S(P))-9b and a monodentate chiral diaminophosphine oxide preligand (S,R(P))-10a, both of which can be prepared from a single chiral source, (S)-L-phenylalanine.

Catalytic Asymmetric Total Synthesis of Tangutorine

The first enantioselective total synthesis of tangutorine has been achieved, wherein a Pd-catalyzed asymmetric allylic amination using a chiral diaminophosphine oxide (DIAPHOX) preligand was the key step.

Kinetic Resolution of Indolines by Pd-Catalyzed Asymmetric Allylic Amination

The kinetic resolution of indolines was realized via a Pd-catalyzed allylic substitution reaction by using Trost's chiral ligand L10, affording optically active indolines and N-allylated indolines in high yields and high enantioselectivities with an S factor up to 59, which provided the first example for the kinetic resolution of nucleophiles via a transition-metal-catalyzed allylic substitution reaction.

Pd‐Catalyzed Asymmetric Allylic Amination Using Aspartic Acid Derived P‐Chirogenic Diaminophosphine Oxides: DIAPHOXs.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A concise and practical catalytic asymmetric synthesis of (−)-CP-99,994 and (−)-L-733,061

A concise and practical catalytic asymmetric synthesis of (−)-CP-99,994 and (−)-L-733,061 was achieved. Key features involve the Pd-catalyzed asymmetric allylic amination and the ring-closing metathesis as key steps.