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1.
Org Lett ; 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32119556

RESUMO

Asymmetric annulation of bench-stable α,ß-unsaturated aryl esters with enamines was realized via cooperative catalysis of chiral isothiourea and Brønsted acid. This reaction proceeds via a chiral α,ß-unsaturated acyl ammonium intermediate and offers a rapid access to functionalized 3,4-dihydropyridin-2-ones in high yields and excellent enantioselectivities.

2.
Top Curr Chem (Cham) ; 378(1): 9, 2019 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-31879793

RESUMO

Asymmetric metal/organo relay catalysis, utilizing a metal complex and a chiral organocatalyst in a one-pot cascade reaction, is aimed to sequentially impart activation on multiple steps by distinct catalysts. Such a catalysis merges the advantages of both metal catalysis and organocatalysis, providing step-economy, and, more importantly, the potential to achieve inaccessible reactivity by a single catalyst. Chiral phosphoric acids are among the most robust organocatalysts, rendering a broad range of enantioselective bond-forming reactions. The combination of metal complexes and chiral phosphoric acids in a single vessel has been well documented. In particular, the asymmetric relay catalysis of metal complex with chiral phosphoric acid has grown rapidly since 2008. Several excellent reviews have been published to cover almost all examples in this area from 2008 to early 2014; therefore, in this chapter, we will mainly highlight progress from 2014 to mid-2019.


Assuntos
Complexos de Coordenação/química , Ácidos Fosfóricos/química , Catálise , Estrutura Molecular , Estereoisomerismo
3.
Angew Chem Int Ed Engl ; 58(47): 16806-16810, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31475764

RESUMO

Branched selectivity in asymmetric allylic C-H alkylation is enabled by using 2-acylimidazoles as nucleophiles in the presence of a chiral phosphoramidite-palladium catalyst. A wide range of terminal alkenes, including 1,4-dienes and allylarenes, are nicely tolerated and provide chiral 2-acylimidazoles in moderate to high yields and with high levels of regio-, and enantio-, and E/Z-selectivities. Mechanistic studies using density-functional theory calculations suggest a nucleophile-coordination-enabled inner-sphere attack mode for the enantioselective carbon-carbon bond-forming event.

4.
Org Lett ; 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31403315

RESUMO

Monodentate phosphorus ligands have been found to enable the palladium-catalyzed allylic C-H alkylation reaction of terminal alkenes with a wide variety of carbon nucleophiles. Moreover, an asymmetric allylic C-H alkylation of terminal alkenes with pyrazol-5-ones has been established in the presence of chiral phosphoramidite ligand and chiral phosphoric acid as co-catalyst. Mechanistic studies suggest that a ternary Pd(0) complex, coordinated with a monodentate phosphorus ligand, benzoquinone, and alkene, is most likely to be an active species.

5.
Angew Chem Int Ed Engl ; 58(35): 12190-12194, 2019 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-31250946

RESUMO

Highly enantioselective [3+3] and [3+4] annulations of isatin-derived enals with ethynylethylene carbonates and ethynyl benzoxazinanones are enabled by NHC/cooper cooperative catalysis, leading to a big library of spirooxindole derivatives in high structural diversity and enantioselectivity (up to 99 % ee). Both reactions represent a nicely synergistic integration of NHC and copper catalysis, in which both catalysts activate the substrates and the chiral NHC perfectly controls the stereochemistry.

6.
J Am Chem Soc ; 141(27): 10616-10620, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31251608

RESUMO

An asymmetric allylic C-H alkylation of allyl ethers has been established by chiral phosphoramidite-palladium catalysis, affording a wide variety of functionalized chiral 2-acylimidazoles in moderate to high yields and with high levels of enantioselectivity. Moreover, this protocol could be applied to a concise asymmetric synthesis of a tachykinin receptor antagonist.

7.
Angew Chem Int Ed Engl ; 58(22): 7450-7453, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-30942948

RESUMO

An enantioselective catalytic alkoxylation/oxidative rearrangement of allylic alcohols has been established by using a Brønsted acid and chiral organoiodine. The presence of 20 mol % of an (S)-proline-derived C2 -symmetric chiral iodine led to enantioenriched α-arylated ß-alkoxylated ketones in good yields and with high levels of enantioselectivity (84-94 % ee).

8.
Angew Chem Int Ed Engl ; 58(23): 7647-7651, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-30972890

RESUMO

A general strategy for the design of asymmetric cascade reactions using readily available halides and carbon monoxide (CO) as substrates is developed. The key is the catalytic generation of C1-ammonium enolates for the subsequent asymmetric cascade reactions through the combination of palladium-catalyzed carbonylation and chiral Lewis base catalysis. Utilizing this strategy, we have established asymmetric formal [1+1+4] and [1+1+2] reactions to afford chiral dihydropyridones and ß-lactams with high yields and high enantio- and diastereoselectivities.

9.
J Am Chem Soc ; 141(14): 5824-5834, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30862155

RESUMO

The asymmetric allylic alkylation (AAA), which features employing active allylic substrates, has historical significance in organic synthesis. The allylic C-H alkylation is principally more atom- and step-economic than the classical allylic functionalizations and thus can be considered a transformative variant. However, asymmetric allylic C-H alkylation reactions are still scarce and yet underdeveloped. Herein, we have found that Z/ E- and regioselectivities in the Pd-catalyzed asymmetric allylic C-H alkylation of 1,4-dienes are highly dependent on the type of nucleophiles. A highly stereoselective allylic C-H alkylation of 1,4-dienes with azlactones has been established by palladium-chiral phosphoramidite catalysis. The protocol proceeds under mild conditions and can accommodate a wide scope of substrates, delivering structurally divergent α,α-disubstituted α-amino acid surrogates in high yields and excellent levels of diastereo-, Z/ E-, regio-, and enantioselectivities. Notably, this method provides key chiral intermediates for an efficient synthesis of lepadiformine marine alkaloids. Experimental and computational studies on the reaction mechanism suggest a novel concerted proton and two-electron transfer process for the allylic C-H cleavage and reveal that the Z/ E- and regioselectivities are governed by the geometry and coordination pattern of nucleophiles.

10.
Org Lett ; 21(7): 2048-2051, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30901225

RESUMO

The first Pd(II)-catalyzed asymmetric oxidative annulation of N-alkoxyaryl amides and 1,3-dienes is reported, which features particular applicability for quick assembly of different types of chiral heterocycles with high yields and enantioselectivities. A novel chiral pyridine-oxazoline bearing a methoxyl group at the C-5 position and a gem-dimethyl group on the oxazoline moiety was found to be crucial for conversion.

11.
Angew Chem Int Ed Engl ; 58(6): 1803-1807, 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30466177

RESUMO

An unusual hybrid palladium catalyst containing an anionic chiral CoIII complex and a chiral phosphoramidite ligand shows a high capacity for catalyzing asymmetric thioamide-directed C(sp3 )-H arylation and delivers excellent yield and enantioselectivity (up to 99 % yield, 99 % ee). Significant synergy between the chiral ligand and the anion in terms of stereochemical control was observed. Mechanistic investigations have revealed both the nature of the C-H activation and the origin of the enantioselectivity.

12.
Org Lett ; 20(16): 4740-4744, 2018 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-30080048

RESUMO

A palladium-catalyzed, enantioselective allylic C-H alkylation of 1,4-pentadienes with 5 H-thiazol-4-ones has been developed. Under the cooperative catalysis of a palladium complex of chiral phosphoramidite ligand and an achiral Brønsted acid, a broad range of substituted 5 H-thiazol-4-ones bearing sulfur-containing tertiary chiral centers were accessed from the allylic C-H alkylation in high levels of yields and enantioselectivities. Alkyl and aryl 1,4-pentadienes led to linear and branched allylation products, respectively.

13.
Chem Commun (Camb) ; 54(69): 9595-9598, 2018 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-30094419

RESUMO

A palladium-catalyzed enantioselective carboannulation of 1,3-dienes and aryl iodides has been established by using a BINOL-based phosphoramidite ligand. This reaction proceeded via a tandem Heck-type insertion and asymmetric intramolecular Tsuji-Trost allylic alkylation, providing indane derivatives with high levels of enantioselectivity (up to >99% ee).

14.
Org Lett ; 20(8): 2403-2406, 2018 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-29620907

RESUMO

A palladium-catalyzed asymmetric α-allylation of aldehydes with alkynes has been established by integrating the catalysis of enamine and chiral hydridopalladium complex that is reversibly formed from the oxidative addition of Pd(0) to chiral phosphoric acid. The ternary catalyst system, consisting of an achiral palladium complex, a primary amine, and a chiral phosphoric acid allows the reaction to tolerate a wide scope of α,α-disubstituted aldehydes and alkynes, affording the corresponding allylation products in high yields and with excellent levels of enantioselectivity.

15.
Org Lett ; 20(8): 2485-2489, 2018 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-29613804

RESUMO

A palladium(II)-catalyzed asymmetric 1,2-diamination of 1,3-dienes with readily available dialkylureas was established by using a chiral pyridine-oxazoline ligand. The diamination reaction exclusively occurs at the terminal C-C double bond of the 1,3-dienes to give 4-vinylimidazolidin-2-ones in high yields and with excellent levels of enantioselectivity (up to 99% yield, 97% ee). The reaction could feasibly be applied for gram-scale synthesis with a 1:1 ratio of the diene and the urea.

16.
Chemistry ; 24(30): 7626-7630, 2018 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-29532578

RESUMO

An efficient synthesis of highly enantio-enriched tetrahydropyrans from readily available aldehydes, allylboronates, and syngas has been established by multiply relay catalysis of rhodium and chiral phosphoric acid. The cascade reaction integrates the asymmetric allylboration of aldehydes and alkene hydroformylation, providing a structurally diverse range of products with different workup procedures. The concise synthesis of key chiral building blocks to access herboxidiene and leucascandrolide A demonstrates the high synthetic utility of this method. The cascade reaction employing alkenes to replace aldehydes was also successful.

18.
Angew Chem Int Ed Engl ; 57(9): 2372-2376, 2018 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-29336513

RESUMO

A PdII -catalyzed asymmetric aminohydroxylation of 1,3-dienes with N-tosyl-2-aminophenols was developed by making use of a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides direct and efficient access to chiral 3,4-dihydro-2H-1,4-benzoxazines in high yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N-tosyl-2-aminophenols as a unique aminohydroxylation reagent and is complementary to known asymmetric aminohydroxylation methods.

19.
J Am Chem Soc ; 140(9): 3177-3180, 2018 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-29377683

RESUMO

An enantioselective α-amination of esters by a Lewis base/copper(I) cooperative catalysis strategy has been developed. The transient chiral C1-ammonium enolate generated from pentafluorophenyl ester and nucleophilic Lewis base is nicely compatible with the copper intermediate formed from N, N-di- t-butyldiaziridinone and Cu(I) to allow for high levels of stereochemical control. The cooperative catalytic reaction leads to a diverse set of highly enantioenriched hydantoins in good yields with excellent enantioselectivities (90-99% ee).

20.
Angew Chem Int Ed Engl ; 56(50): 16032-16036, 2017 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-29063650

RESUMO

A palladium-catalyzed asymmetric intramolecular allylic C-H amination controlled by a chiral phosphoramidite ligand was established for the preparation of various substituted chiral hydropyrimidinones, the precursors of hydropyrimidines, in high yields with high enantioselectivities. In particular, dienyl sodium N-sulfonyl amides bearing an arylethene-1-sulfonyl group underwent a sequential allylic C-H amination and intramolecular Diels-Alder (IMDA) reaction to produce chiral fused tricyclic tetrahydropyrimidinone frameworks in high yields and with high levels of stereoselectivity. Significantly, this method was used as the key step in an asymmetric synthesis of letermovir.

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