tert-Butanesulfinylthioether ligands: synthesis and application in palladium-catalyzed asymmetric allylic alkylation

Liu, Jibing; Chen, Guihua; Xing, Junwei; Liao, Jian

doi:10.1016/j.tetasy.2011.02.031

Cited by 34 publications

(19 citation statements)

References 24 publications

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“…Although it was found that the ( S,S )‐ i Pr‐phosferrox ligand gave the best results for the palladium‐catalyzed AAA of dimethyl malonate in terms of enantioselectivity (92 % ee and 31 % yield), the catalytic allylic alkylation of methyl 2‐cyanoacetate led to poor diastereoselectivity (1:1 dr ), and the enantiomeric excess ( ee ) of the product was not determined (Scheme ). Only in 2011 did Liao and co‐workers report the synthesis of a new class of S,O,S bidentate ligands for the asymmetric allylic allylation of malonates and 1 a 6b. Although only moderate yield and enantioselectivity were obtained for 1 a , the diastereoselectivity in this reaction was excellent (>50:1 dr ).…”

Section: Methodsmentioning

confidence: 99%

Multistereogenic Phosphine Ligand‐promoted Palladium‐Catalyzed Allylic Alkylation of Cyanoesters

Deng¹,

Ye²,

Bai³

et al. 2014

ChemCatChem

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A palladium-catalyzed allylic alkylation of unsubstituted 2-cyanoacetates using a 1,1'-bi-2-naphthol-derived multifunctional N,O,P ligand is reported. A number of chiral monosubstituted 2-cyanoacetates with two adjacent stereogenic carbon centers are obtained in this Pd-catalyzed asymmetric allylic alkylation reaction, in which the multistereogenic and multifunctional 1,1'-bi-2-naphthol-derived N,O,P ligand-promoted Pd-catalyzed asymmetric allylic alkylation reaction proceeds smoothly in high diastereo-and enantioselectivity (up to > 99:1 dr and up to 96 % ee).The allylic alkylation of carbon-based nucleophiles to allylic reagents, including allylic acetates, is one of the most important methods for carbon-carbon bond construction.[1] Accordingly, the development of catalytic asymmetric versions of this type of transformation and the design and application of various ligands for enantioselectivity enhancement have been the subject of intensive research in the field of asymmetric catalysis and organic chemistry over the past decades. [2][3][4] In this respect, the asymmetric allylic alkylation (AAA) of activated methylene compounds, such as 1,3-dicarbonyl compounds, is very important and one of the most attractive approaches to the synthesis of chiral carbonyl derivatives. [3,4] To attain high stereoselectivity, numerous chiral ligands, especially P ligands, have been developed. [4] In addition, similarly to catalytic asymmetric hydrogenation, the catalytic AAA of 1,3-dicarbonyl compounds has been applied extensively as a model reaction in the evaluation of chiral ligands in asymmetric catalysis, which would be beneficial to the exploration of novel backbones or strategies for chiral ligand chemistry. Despite the development of various well-defined palladium catalysts derived from chiral ligands for this AAA reaction, effective chiral ligands were still lacking for the allylic alkylation of unsubstituted 2-cyanoacetates, [5, 6] for example, only ethyl 2-cyanoacetate (1 a) or methyl 2-cyanoacetate has attracted limited attention in the past decades. To the best of our knowledge, there are only a few examples of the asymmetric palladium-catalyzed allylic alkylation of unsubstituted 2-cyanoaetates with allylic acetates.[6] Unfortunately, the enantioselectivities in these reported reactions were not good enough, possibly as a result of the difficulty in forming two adjacent stereogenic centers simultaneously from two substrates.As shown in Scheme 1, these reported methods involving chiral ligands bearing a phosphine, sulfur, or oxazoline moiety did not achieve a high level of enantioselectivity. Notably, in combination with the application of ionic liquids in catalysis, Scheme 1. Previous results and this work on the catalytic AAA reaction of 2-cyanoacetates. dba = Dibenzylideneacetone, bmim = 1-butyl-3-methylimidazolium.[a] W

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Section: Methodsmentioning

confidence: 99%

Multistereogenic Phosphine Ligand‐promoted Palladium‐Catalyzed Allylic Alkylation of Cyanoesters

Deng¹,

Ye²,

Bai³

et al. 2014

ChemCatChem

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“…A subsequent report from Liao et al. demonstrated that replacement of the aryl thioether with an alkyl substituent, modification of the phenylene linker, and use of a tert ‐butylsulfinyl group on the ligand ( 78 ) resulted in the formation of adduct 19 in 98 % yield and 80 % ee 41. Strangely, the use of sulfoxides with opposite configurations resulted in the formation of the same product enantiomer, though neither of the authors commented on this discrepancy.…”

Section: Ss Ligandsmentioning

confidence: 99%

Development of Chiral Sulfoxide Ligands for Asymmetric Catalysis

2015

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Nitrogen-, phosphorus-, and oxygen-based ligands with chiral backbones have been the historic workhorses of asymmetric transition-metal-catalyzed reactions. On the contrary, sulfoxides containing chirality at the sulfur atom have mainly been used as chiral auxiliaries for diastereoselective reactions. Despite several distinct advantages over traditional ligand scaffolds, such as the proximity of the chiral information to the metal center and the ability to switch between S and O coordination, these compounds have only recently emerged as a versatile class of chiral ligands. In this Review, we detail the history of the development of chiral sulfoxide ligands for asymmetric catalysis. We also provide brief descriptions of metal-sulfoxide bonding and strategies for the synthesis of enantiopure sulfoxides. Finally, insights into the future development of this underutilized ligand class are discussed.

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“…Aryl tert-butyl sulfoxides 1a-c were therefore prepared following Ellman's method, 41,42 after enantioselective oxidation of di-tert-butyl disulfide and treatment with the desired aryllithium reagents (Scheme 3). Sulfoxide 1a was chosen as the test substrate in the 'ARYNE coupling' with 1,2-dibromobenzene due to its easy access, its completely regioselective lithiation with nBuLi, 43,44 and the ease of detection of its derivatives by 1 H and 13 C NMR thanks to the OMe signals. Preliminary experiments showed that under the previously reported conditions (treatment of the pronucleophile with nBuLi at −78 °C, followed by addition of 1,2-dibromobenzene at −78 °C and stirring while warming up to room temperature) no coupling product was obtained (Table 1, entry 1).…”

Section: Atropo-diastereoselective 'Aryne Coupling' With Aryl Tert-bu...mentioning

confidence: 99%

Atroposelective synthesis of axially chiral P,S-ligands based on arynes

et al. 2015

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The first atropo-selective aryl-aryl coupling based on arynes in the presence of a tert-butylsulfinyl group as the chiral auxiliary on the aryllithium nucleophile is described. The approach allows for the efficient access to a novel family of atropo-enantiopure biphenyl-based phosphine-thioether ligands. The new P,S heterodonor ligands were assessed in model palladium-catalyzed allylic substitution reactions.

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tert-Butanesulfinylthioether ligands: synthesis and application in palladium-catalyzed asymmetric allylic alkylation

Cited by 34 publications

References 24 publications

Multistereogenic Phosphine Ligand‐promoted Palladium‐Catalyzed Allylic Alkylation of Cyanoesters

Multistereogenic Phosphine Ligand‐promoted Palladium‐Catalyzed Allylic Alkylation of Cyanoesters

Development of Chiral Sulfoxide Ligands for Asymmetric Catalysis

Atroposelective synthesis of axially chiral P,S-ligands based on arynes

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