Month: February 2023

Palladium Catalyzed Kinetic and Dynamic Kinetic Asymmetric Transformations of γ-Acyloxybutenolides. Enantioselective Total Synthesis of (+)-Aflatoxin B₁ and B_2a was written by Trost, Barry M.;Toste, F. Dean. And the article was included in Journal of the American Chemical Society in 2003.Related Products of 174810-09-4 This article mentions the following:

The reaction of γ-tert-butoxycarbonyloxy-2-butenolide with phenol nucleophiles in the presence of a Pd(0) complex with chiral ligands may be performed under conditions that favor either a kinetic resolution or a kinetic asym. transformation (KAT) or dynamic kinetic asym. transformation (DYKAT). Performing the reaction at high concentration (0.5 M) in the presence of a carbonate base favors the former, i.e., KAT; whereas, running the reaction at 0.1M in the presence of tetra-n-butylammonium chloride favors the DYKAT process. Syntheses of aflatoxin B₁ (I) and B_2a (II) employs the DYKAT to introduce the stereochem. Starting with Pechmann condensation of the monomethyl ether of phloroglucinol, the requisite phenol nucleophile is constructed in two steps. The DYKAT proceeds with > 95% ee. A reductive Heck cyclization followed by a lanthanide catalyzed intramol. acylation completes the synthesis of the pentacyclic nucleus in 3 steps. Reduction of the lactone provides aflatoxin B_2a and its dehydration product B₁. This synthetic strategy creates an asym. synthesis of the former in only 7 steps and the latter in 9 steps. Thus, the ultimate synthetic sequence involves butenolide III (Boc = CO₂CMe₃) and 5-methoxybenzene-1,3-diol via pyranones IV (X = H, I), butenolide V, and furofuranones VI, VII and VIII, giving II and then I. In the experiment, the researchers used many compounds, for example, N,N’-((1R,2R)-Cyclohexane-1,2-diyl)bis(2-(diphenylphosphino)-1-naphthamide) (cas: 174810-09-4Related Products of 174810-09-4).

N,N’-((1R,2R)-Cyclohexane-1,2-diyl)bis(2-(diphenylphosphino)-1-naphthamide) (cas: 174810-09-4) belongs to chiral phosphine ligands. Many phosphine-catalyzed reactions have been developed for the syntheses of various biologically important acyclic and cyclic molecules. Asymmetric variants of these reactions have evolved relatively slowly. Chiral ligands coordinate to metal centers to create an asymmetric environment around the reaction centers, which eventually affects enantioselectivity and reaction rate.Related Products of 174810-09-4

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Interactions of cationic palladium(II)- and platinum(II)-η³-allyl complexes with fluoride: is asymmetric allylic fluorination a viable reaction? was written by Hintermann, Lukas;Lang, Florian;Maire, Pascal;Togni, Antonio. And the article was included in European Journal of Inorganic Chemistry in 2006.Name: (R)-N,N-Dimethyl-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethylamine This article mentions the following:

The origin of dramatic anion effect on palladium-catalyzed asym. allylic substitution, an improvement of enantioselectivity caused by fluoride additives, was explored by reacting of fluoride anions from different sources with pre-formed palladium and platinum allyl complexes. The complex cations [M(η³-RCH:CHCHR)(L₂-N,P)]⁺ (M = Pd, R = Ph, Cy; RCH:CHCHR = indenyl; M = Pt, R = Ph; L₂ = 3-tert-butyl-1-[1-[2-diphenylphosphinoferrocenyl]ethyl]-1H-pyrazole [PPFPz-3-^tBu]) were prepared as salts with PF₆^– or SbF₆^–. The cations were characterized by NMR spectroscopy in solution and by x-ray crystallog. in the solid state. Their reactions with sources of nucleophilic and “naked” fluoride were investigated by multinuclear NMR spectroscopy. The Pd allyl complexes did not undergo any nucleophilic substitution with concomitant release of allyl fluorides. The dicyclohexylallyl fragment was released as a 1,3-diene, 1-cyclohexyl-3-cyclohexylidene-1-propene, by fluoride-induced elimination, but for other allyl complexes the fluoride anions caused rather non-specific decomposition The complex [Pt(η³-1,3-Ph₂C₃H₃)(L₂-N,P)]PF₆ underwent an anion exchange with Me₄NF to give [Pt(1,3-Ph₂C₃H₃)(L₂-N,P)]F which existed as a mixture of interconverting allyl isomers in solution at ambient temperature For similar bromide salt, [Pt(η³-1,3-Ph₂C₃H₃)(L₂-N,P)]Br, allyl isomerization was slow at ambient temperature Precursors of Pt(0) reacted with 3-bromo-1,3-diphenyl-1-propene to give [Pt₂(μ-Br)₂(η³-1,3-Ph₂C₃H₃)₂] and precursors of Pd(0) underwent oxidative additions with both 3-bromo- and 3-fluoro-1,3-diphenyl-1-propenes to give 1,3-diphenylallyl complexes of Pd(II). Therefore, the nucleophilic attack of fluoride on the allyl fragment of Pd(II) complexes is endergonic and thermodynamically unfavored, and the high energy barrier of this step is difficult to overcome in a catalytic allylic fluorination reaction. In the experiment, the researchers used many compounds, for example, (R)-N,N-Dimethyl-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethylamine (cas: 55700-44-2Name: (R)-N,N-Dimethyl-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethylamine).

(R)-N,N-Dimethyl-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethylamine (cas: 55700-44-2) belongs to chiral phosphine ligands. Phosphine-catalyzed asymmetric reactions are now powerful and versatile tools for the construction of C–C, C–N, C–O, and C–S bonds and for the syntheses of functionalized carbocycles and heterocycles. Chiral phosphine catalysts: Nucleophilic phosphine catalysis often involves the formation of Lewis adducts, namely phosphonium (di)enolate zwitterions, as reaction intermediates.Name: (R)-N,N-Dimethyl-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethylamine

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Thioketone-directed rhodium(I) catalyzed enantioselective C-H bond arylation of ferrocenes was written by Cai, Zhong-Jian;Liu, Chen-Xu;Wang, Qiang;Gu, Qing;You, Shu-Li. And the article was included in Nature Communications in 2019.Formula: C31H32O2P2 This article mentions the following:

Planar chiral ferrocenes have received great attention in both academia and industry. Although remarkable progresses have been made over the past decade, the development of efficient and straightforward methods for the synthesis of enantiopure planar chiral ferrocenes remains highly challenging. Herein, authors report a rhodium(I)/phosphonite catalyzed thioketone-directed enantioselective C-H bond arylation of ferrocenes. Readily available aryl iodides are used as the coupling partners in this transformation, leading to a series of planar chiral ferrocenes in good yields and excellent enantioselectivities (up to 86% yield, 99% ee). Of particular note, heteroaryl coupled ferrocenes, which are difficult to access with previous approaches, can be obtained in satisfactory results. In the experiment, the researchers used many compounds, for example, (((4S,5S)-2,2-Dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene))bis(diphenylphosphine) (cas: 37002-48-5Formula: C31H32O2P2).

(((4S,5S)-2,2-Dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene))bis(diphenylphosphine) (cas: 37002-48-5) belongs to chiral phosphine ligands. The synthesis of novel trialkylphosphines can be quite difficult, thereby limiting the scope of their chiral variants. Trivalent phosphorus compounds called phosphines have a tetrahedral electron-group geometry which makes them structurally analogous to amines.Formula: C31H32O2P2

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Asymmetric cyclocarbonylation of 1,6-enynes with cobalt catalysts was written by Schmid, Thomas M.;Consiglio, Giambattista. And the article was included in Tetrahedron: Asymmetry in 2004.Category: chiral-phosphine-ligands This article mentions the following:

Octacarbonyldicobalt or Co(II) salts in the presence of (R)-(6,6′-dimethoxybiphenyl-2,2′-diyl)bis(diphenylphosphine) were active and highly enantioselective catalyst for the cyclocarbonylation of enynes such as 4,4-bis(carboethoxy)hex-6-en-1-yne. The reactivity of both catalytic systems towards cyclocarbonylation increased when the CO pressure was increased. However, when a stoichiometric amount of ligand was used, with respect to the catalyst, the enantioselectivity decreased, but increased again as the ligand-to-Co molar ratio increased. In the experiment, the researchers used many compounds, for example, (R)-(6,6′-Dimethoxy-[1,1′-biphenyl]-2,2′-diyl)bis(diphenylphosphine) (cas: 133545-16-1Category: chiral-phosphine-ligands).

(R)-(6,6′-Dimethoxy-[1,1′-biphenyl]-2,2′-diyl)bis(diphenylphosphine) (cas: 133545-16-1) belongs to chiral phosphine ligands. The synthesis of novel trialkylphosphines can be quite difficult, thereby limiting the scope of their chiral variants. Asymmetric catalytic performance is determined not only by the metal center but also by the chiral ligand selected.Category: chiral-phosphine-ligands

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Rapid ketone transfer hydrogenation by employing simple, in situ prepared iridium(I) precatalysts supported by “non-N-H” P,N ligands was written by Lundgren, Rylan J.;Stradiotto, Mark. And the article was included in Chemistry – A European Journal in 2008.Quality Control of (R,R)-2,2′-Bis[(R)-(N,N-dimethylamino)(phenyl)methyl]-1,1′-bis(diphenylphosphino)ferrocene This article mentions the following:

The catalytic utility in ketone transfer hydrogenation (TH) of the preformed [Ir(cod)(κ²-2-NMe₂-3-PiPr₂-indene)]⁺X^– ([2a]⁺X^–; X: PF₆, BF₄, and OTf; cod: η⁴-1,5-cyclooctadiene; OTf: trifluoromethanesulfonate), [Ir(cod)(κ²-1-PiPr₂-2-NMe₂-indene)]⁺OTf^– ([2b]⁺OTf^–), [Ir(cod)(κ²-2-NMe₂-3-PiPr₂-indenide)] (3), and [Ir(cod)(κ²-o-tBu₂PC₆H₄NMe₂)]⁺PF₆^– ([4]⁺PF₆^–), and of related mixtures prepared from [{IrCl(cod)}₂] and various P,N-substituted indene or phenylene ligands, was examined Whereas [2a]⁺X^–, [2b]⁺OTf^–, 3, and related in situ prepared Ir catalysts derived from P,N-indenes proved to be generally effective in mediating the reduction of acetophenone to 1-phenylethanol in basic iPrOH at reflux (0.1 mol% Ir; 81-99% conversion) in a preliminary catalytic survey, the structurally related Ir catalysts prepared from (o-R₂PC₆H₄)NMe₂ (R: Ph, iPr, or tBu) outperform the corresponding P,N-indene ligands under similar conditions. In such studies, alteration of the substituents at the donor fragments of the supporting P,N ligand had a pronounced influence on the catalytic performance of the derived catalysts, with ligands featuring bulky dialkylphosphino donors proving to be the most effective. Notably, the crystallog. characterized complex [4]⁺PF₆^–, either preformed or prepared in situ from a mixture of [{IrCl(cod)}₂], NaPF₆, and (o-tBu₂PC₆H₄)NMe₂, proved to be highly effective in mediating the catalytic transfer hydrogenation (TH) of ketones in basic iPrOH, with near quant. conversions for a range of alkyl and/or aryl ketones and with very high turnover-frequency values (up to 230000 h^-1 at > 50% conversion); this thereby enabled the use of Ir loadings ranging from 0.1 to 0.004 mol %. Catalyst mixtures prepared from [{IrCl(cod)}₂], NaPF₆, and the chiral (αS,αS)-1,1′-bis[α-(dimethylamino)benzyl]-(R,R)-2,2′-bis(dicyclohexylphosphino)ferrocene (Cy-Mandyphos) ligand proved capable of mediating the asym. TH of aryl alkyl ketones, including that of the hindered substrate 2,2-dimethylpropiophenone with an efficiency (0.5 mol% Ir; 95% conversion, 95% ee) not documented previously in TH chem. In the experiment, the researchers used many compounds, for example, (R,R)-2,2′-Bis[(R)-(N,N-dimethylamino)(phenyl)methyl]-1,1′-bis(diphenylphosphino)ferrocene (cas: 174467-31-3Quality Control of (R,R)-2,2′-Bis[(R)-(N,N-dimethylamino)(phenyl)methyl]-1,1′-bis(diphenylphosphino)ferrocene).

(R,R)-2,2′-Bis[(R)-(N,N-dimethylamino)(phenyl)methyl]-1,1′-bis(diphenylphosphino)ferrocene (cas: 174467-31-3) belongs to chiral phosphine ligands. Thousands of arylphosphines have been used as chiral ligands for metal-catalyzed asymmetric reactions. Indeed, very little research on chiral tertiary phosphine-catalyzed asymmetric reactions occurred prior to the year 2000.Quality Control of (R,R)-2,2′-Bis[(R)-(N,N-dimethylamino)(phenyl)methyl]-1,1′-bis(diphenylphosphino)ferrocene

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Homogeneous Chiral Nickel-Catalyzed Asymmetric Hydrogenation of Substituted Aromatic α-Aminoketone Hydrochlorides through Dynamic Kinetic Resolution was written by Hibino, Takuya;Makino, Kazuishi;Sugiyama, Takaya;Hamada, Yasumasa. And the article was included in ChemCatChem in 2009.Application of 360048-63-1 This article mentions the following:

Asym. hydrogenation of aromatic amino ketones using homogeneous chiral nickel catalyst proceeds with high diastereoselectivity and excellent enantioselectivity via dynamic kinetic resolution In AcOH the hydrogenation proceeds diastereoselectively with retention of the configuration at the stereogenic center. In the experiment, the researchers used many compounds, for example, (1R)-1-[Bis(4-methoxy-3,5-dimethylphenyl)phosphino]-2-[(1R)-1-(dicyclohexylphosphino)ethyl]ferrocene (cas: 360048-63-1Application of 360048-63-1).

(1R)-1-[Bis(4-methoxy-3,5-dimethylphenyl)phosphino]-2-[(1R)-1-(dicyclohexylphosphino)ethyl]ferrocene (cas: 360048-63-1) belongs to chiral phosphine ligands. Although many reactions require more nucleophilic trialkylphosphines as catalysts, only a few chiral trialkylphosphines are available. Trivalent phosphorus compounds called phosphines have a tetrahedral electron-group geometry which makes them structurally analogous to amines.Application of 360048-63-1

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Ir(I)-catalyzed enantioselective hydrogenolysis of 3-aryl-3-hydroxyisoindolin-1-ones was written by Ge, Chen;Liang, Ren-Xiao;Liu, Ren-Rong;Xiang, Bin;Jia, Yi-Xia. And the article was included in Tetrahedron Letters in 2017.Reference of 133545-16-1 This article mentions the following:

An enantioselective hydrogenolysis of 3-aryl-3-hydroxyisoindolin-1-ones under H₂ was developed by using Ir(I)/(R)-MeO-Biphep complex as a catalyst. Cyclic diaryl methylamides were obtained in moderate to excellent yields and up to 92% ee. In the experiment, the researchers used many compounds, for example, (R)-(6,6′-Dimethoxy-[1,1′-biphenyl]-2,2′-diyl)bis(diphenylphosphine) (cas: 133545-16-1Reference of 133545-16-1).

(R)-(6,6′-Dimethoxy-[1,1′-biphenyl]-2,2′-diyl)bis(diphenylphosphine) (cas: 133545-16-1) belongs to chiral phosphine ligands. Generally, the efficiency of nucleophilic phosphine catalysis often depends on the nature of the tertiary phosphine. Asymmetric catalytic performance is determined not only by the metal center but also by the chiral ligand selected.Reference of 133545-16-1

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Catalytic Enantioselective Hydrovinylation of Trialkylsilyloxy and Acetoxy-1,3-Dienes: Cationic Co(I) Complexes for the Synthesis of Chiral Enolate Surrogates and Their Applications for Synthesis of Ketones and Cross-Coupling Reagents in High Enantiomeric Purity was written by Biswas, Souvagya;Dewese, Kendra R.;Raya, Balaram;RajanBabu, T. V.. And the article was included in ACS Catalysis in 2022.Name: (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine) This article mentions the following:

(E)-2-Trialkylsilyloxy-1,3-dienes and the corresponding 2-acetoxy derivatives participate in Co-catalyzed heterodimerization reactions with ethylene, giving mostly 4,1-hydrovinylation products with addition of the vinyl group to C₄ and H at C₁ of the diene. The reaction, which gives highly functionalized, protected enolates, is best carried out at room temperature with the diene dissolved in CH₂Cl₂ and ethylene delivered from a balloon in the presence of a catalyst generated in situ by the reaction of (P~P)CoCl₂ with methylaluminoxane (MAO). Com. available chiral ligands, 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis-(diphenylphosphino)butane (DIOP) and 2,4-bis-diphenylphosphinopentane (BDPP) in combination with the earth-abundant metal Co, gave excellent regio- and enantioselectivities (up to 99% ee) for the chiral enolate surrogates from both silyloxy and acetoxydienes. Hydrolyzes of the silyl enol ethers lead to β-vinyl ketones, thus providing a practical two-step approach to these valuable synthons starting from α,β-unsaturated ketones and ethylene. The hydrovinylated silyl enol ethers undergo typical nucleophilic reactions such as alkylation, aldol, and Michael and Mannich reactions with varying degrees of diastereoselectivity (2:1-13:1). The silyl enol ethers are convenient sources of Li enolates, which are readily converted into other vinyl derivatives such as vinyl acetates and vinyl triflates. The vinyl triflates are excellent partners for cross-coupling chem., giving potentially useful, polyolefinic chiral synthons for further applications. Chemoselective reduction and hydrosilylation of the vinyl group in the chiral β-vinyl silyl enol ether further illustrate other potential reactivities of these versatile synthons. Since isolated cationic [(P~P)Co(I)]⁺ [BARF]^– appears to be an excellent catalyst for the heterodimerization of silyl enol ethers and ethylene giving products very similar in yield and selectivities to what is observed in the MAO-mediated reactions, probably a previously invoked Co(I)/Co(III) cycle, common to other similar heterodimerization reactions, might be involved in these reactions as well. In the experiment, the researchers used many compounds, for example, (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine) (cas: 77876-39-2Name: (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine)).

(2S,4S)-Pentane-2,4-diylbis(diphenylphosphine) (cas: 77876-39-2) belongs to chiral phosphine ligands. Many phosphine-catalyzed reactions have been developed for the syntheses of various biologically important acyclic and cyclic molecules. Asymmetric variants of these reactions have evolved relatively slowly. Asymmetric catalytic performance is determined not only by the metal center but also by the chiral ligand selected.Name: (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine)

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Chiral discrimination at the η³-allyl units of rhodium(I) η³-cyclooctenyl complexes containing chiral bidentate phosphines was written by Lange, Susanne;Wittmann, Klaus;Gabor, Barbara;Mynott, Richard;Leitner, Walter. And the article was included in Tetrahedron: Asymmetry in 1998.Recommanded Product: (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine) This article mentions the following:

A three step synthesis of Rh(I) η³-cyclooctenyl complexes [(P₂^*)Rh(η³-C₈H₁₃)] (P₂^* = chiral bidentate phosphine, e.g. (S,S)-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxolane) starting from com. available [{(cod)Rh(μ-Cl)}₂] is described. Examination of these complexes by multinuclear NMR-spectroscopy reveals a distinct stereochem. differentiation of the terminal positions of the η³-allyl unit. Preliminary results on the reactivity of these compounds towards various electrophiles E-X (e.g. MeOTf) are reported; hydrogen transfer is preferred over formation of C-E bonds. In the experiment, the researchers used many compounds, for example, (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine) (cas: 77876-39-2Recommanded Product: (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine)).

(2S,4S)-Pentane-2,4-diylbis(diphenylphosphine) (cas: 77876-39-2) belongs to chiral phosphine ligands. The synthesis of novel trialkylphosphines can be quite difficult, thereby limiting the scope of their chiral variants. Over the last decade, however, and especially since 2005, considerable progress has been made in asymmetric phosphine catalysis.Recommanded Product: (2S,4S)-Pentane-2,4-diylbis(diphenylphosphine)

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Enantioselective α-Allylation of Anilines Enabled by a Combined Palladium and Photoredox Catalytic System was written by Zhang, Hong-Hao;Zhao, Jia-Jia;Yu, Shouyun. And the article was included in ACS Catalysis in 2020.HPLC of Formula: 352655-61-9 This article mentions the following:

An enantioselective and branch-regioselective α-allylation of N-Me anilines with allylic acetates under dual palladium/photoredox catalysis was described. Readily available N-Me anilines were used as formal ”hard” alkyl nucleophiles without preactivation. Acetic acid was the only side product, which led to a high atom economy of this reaction. This protocol showed good functional group tolerance and broad scope. A range of chiral homoallylic amines I [R = Me, i-Pr, Ph, etc.; Ar¹ = Ph, 4-MeOC₆H₄, 4-NHAcC₆H₄, etc.; Ar² = Ph, 3-MeC₆H₄, 4-ClC₆H₄, etc.] were prepared in moderate to good yields (up to 76%) and excellent regioselectivities (B:L > 95:5 in all cases) and enantioselectivities (up to 96% ee) under mild reaction conditions. In the experiment, the researchers used many compounds, for example, (R)-(-)-2,2′-Bis[di(3,5-di-t-butyl-4-methoxyphenyl)phosphino]-6,6′-dimethoxy-1,1′-biphenyl (cas: 352655-61-9HPLC of Formula: 352655-61-9).

(R)-(-)-2,2′-Bis[di(3,5-di-t-butyl-4-methoxyphenyl)phosphino]-6,6′-dimethoxy-1,1′-biphenyl (cas: 352655-61-9) belongs to chiral phosphine ligands. Phosphine-catalyzed asymmetric reactions are now powerful and versatile tools for the construction of C–C, C–N, C–O, and C–S bonds and for the syntheses of functionalized carbocycles and heterocycles. Chiral phosphine catalysts: Nucleophilic phosphine catalysis often involves the formation of Lewis adducts, namely phosphonium (di)enolate zwitterions, as reaction intermediates.HPLC of Formula: 352655-61-9

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis