Tag: 300-400

Chiral Norbornadienes as Efficient Ligands for the Rhodium-Catalyzed Asymmetric 1,4-Addition of Arylboronic Acids to Fumaric and Maleic Compounds was written by Shintani, Ryo;Ueyama, Kazuhito;Yamada, Ichiro;Hayashi, Tamio. And the article was included in Organic Letters in 2004.Recommanded Product: 252288-04-3 This article mentions the following:

A rhodium-catalyzed asym. 1,4-addition of arylboronic acids to fumaric and maleic compounds has been developed. While phosphorus-based chiral ligands fail to induce high stereoselectivity, chiral norbornadiene ligands have proved to be uniquely effective to achieve high enantioselectivity in these 1,4-addition reactions. In an example reaction, di-tert-Bu fumarate reacted with phenylboronic acid in the presence of (1R,4R)-2,5-di(2,4,6-trimethylphenylmethyl)bicyclo[2.2.1]hepta-2,5-diene giving (S)-di-tert-Bu phenylbutanedioate (90% yield, 90% ee). The structure of [RhCl(1)]₂ (1 = (1R,4R)-2,5-di(phenylmethyl)bicyclo[2.2.1]hepta-2,5-diene) was determined by x-ray crystallog. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Recommanded Product: 252288-04-3).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) 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. Over the last decade, however, and especially since 2005, considerable progress has been made in asymmetric phosphine catalysis.Recommanded Product: 252288-04-3

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Boryl-Dictated Site-Selective Intermolecular Allylic and Propargylic C-H Amination was written by Liu, Yuan;Chen, Zhi-Hao;Li, Yin;Qian, Jiasheng;Li, Qingjiang;Wang, Honggen. And the article was included in Journal of the American Chemical Society in 2022.SDS of cas: 252288-04-3 This article mentions the following:

For internal alkenes possessing two or more sets of electronically and sterically similar allylic protons, the site-selectivity for allylic C-H functionalization is fundamentally challenging. Previously, the neg. inductive effect from an electroneg. atom is effective for several inspiring regioselective C-H functionalization reactions. Yet, the use of an electropos. atom for a similar purpose remains to be developed. α-Aminoboronic acids and their derivatives found widespread applications. Their current syntheses rely heavily on functional group manipulations. Herein the authors report a boryl-directed intermol. C-H amination of allyl N-methyliminodiacetyl boronates (B(MIDA)s) and propargylic B(MIDA)s to give α-amino boronates with an exceptionally high level of site-selectivities (up to 300:1). A wide variety of highly functionalized secondary and tertiary α-amino boronates are formed in generally good to excellent yields, thanks to the mildness of the reaction conditions. The unsaturated double and triple bonds within the product leave room for further decorations. Mechanistic studies reveal that the key stabilization effect of the B(MIDA) moiety on its adjacent developing pos. charge is responsible for the high site-selectivity and that a closed transition state might be involved, as the reaction is fully stereoretentive. An activation effect of B(MIDA) is also found. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3SDS of cas: 252288-04-3).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. At present, the synthesis of new chiral phosphines designed specifically for nucleophilic organocatalysis remains a significant challenge. Effective chiral catalysts for nucleophilic phosphine catalysis are scarce, seriously limiting the development of asymmetric variants. SDS of cas: 252288-04-3

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Asymmetric Pauson-Khand reaction with chiral, electron-deficient mono- and bis-phosphine ligands was written by Konya, Denes;Robert, Frederic;Gimbert, Yves;Greene, Andrew E.. And the article was included in Tetrahedron Letters in 2004.HPLC of Formula: 252288-04-3 This article mentions the following:

The intermol. Pauson-Khand reaction between norbornene and dicobalt carbonyl complexes of phenylacetylene substituted with chiral phosphorus ligands has been investigated. I was obtained in high yield and good enantiomeric excess. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3HPLC of Formula: 252288-04-3).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. Although many reactions require more nucleophilic trialkylphosphines as catalysts, only a few chiral trialkylphosphines are available. Over the last decade, however, and especially since 2005, considerable progress has been made in asymmetric phosphine catalysis.HPLC of Formula: 252288-04-3

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Direct visual detection of the stereoselectivity of a catalytic reaction was written by Eelkema, Rienk;van Delden, Richard A.;Feringa, Ben L.. And the article was included in Angewandte Chemie, International Edition in 2004.Reference of 252288-04-3 This article mentions the following:

Color vision: the enantiomeric excess of the products of an enantioselective catalytic reaction can be determined by a liquid-crystal-based color test. After a simple workup, doping of the reaction product into a liquid crystal affords brightly colored LC phases, with colors depending on the enantiomeric excess of the product. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Reference of 252288-04-3).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. Generally, the efficiency of nucleophilic phosphine catalysis often depends on the nature of the tertiary phosphine. Chiral ligands coordinate to metal centers to create an asymmetric environment around the reaction centers, which eventually affects enantioselectivity and reaction rate.Reference of 252288-04-3

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

C₂-symmetric bicyclo[3.3.1]nonadiene as a chiral ligand for rhodium-catalyzed asymmetric arylation of N-(4-nitrobenzenesulfonyl)arylimines was written by Otomaru, Yusuke;Tokunaga, Norihito;Shintani, Ryo;Hayashi, Tamio. And the article was included in Organic Letters in 2005.Synthetic Route of C24H22NO2P This article mentions the following:

Nonracemic (+)-2,6-diphenylbicyclo[3.3.1]-2,6-nonadiene (I) is prepared in two steps from 2,6-bicyclo[3.3.1]nonanedione; complex {Rh[(+)-I]₂Cl}₂ (II) is an effective catalyst for the addition of arylboroxines [(R)BO]₃ (R = Ph, 4-ClC₆H₄, 4-MeOC₆H₄, 3-MeOC₆H₄, 2-MeC₆H₄) to N-(4-nitrobenzenesulfonyl)imines R¹C(:NNs)H (R¹ = Ph, 4-ClC₆H₄, 4-BrC₆H₄, 4-MeO₂CC₆H₄, 4-MeOC₆H₄, 2-MeC₆H₄, 1-naphthyl, 2-thienyl; Ns = 4-O₂NC₆H₄SO₂) to yield nonracemic diarylmethylamines RCH(NHNs)R¹ in 94-99% yields and in 95-99% ee. Addition of phenyllithium and cerium chloride to 2,6-bicyclo[3.3.1]nonanedione followed by phosphorus oxychloride-mediated elimination yields racemic I which is resolved by chiral HPLC to yield (+)-I; reaction of (+)-I with [Rh(C₂H₄)₂Cl]₂ yields II. Catalysts generated in situ from bisphosphines and [Rh(C₂H₄)₂Cl]₂ are ineffective for the enantioselective addition reaction; catalysts generated from either a binaphthyldiol phosphoramidite or nonracemic bicyclic dienes and [Rh(C₂H₄)₂Cl]₂ catalyze the enantioselective addition but with lower enantioselectivities than II. Deprotection of the 4-nitrobenzenesulfonyl group with benzenethiol and potassium carbonate in DMF yields the free diarylmethylamines in two cases with no loss of enantioselectivity. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Synthetic Route of C24H22NO2P).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. Although many reactions require more nucleophilic trialkylphosphines as catalysts, only a few chiral trialkylphosphines are available. Most of these phosphines are acyclic, usually possess low nucleophilic activity, and generally display poor enantioselectivities for phosphine organocatalysis. Synthetic Route of C24H22NO2P

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Carbon-Carbon Bond-Forming Enantioselective Synthesis of Chiral Organosilicon Compounds by Rhodium/Chiral Diene-Catalyzed Asymmetric 1,4-Addition Reaction was written by Shintani, Ryo;Okamoto, Kazuhiro;Hayashi, Tamio. And the article was included in Organic Letters in 2005.Reference of 252288-04-3 This article mentions the following:

A new synthetic method for chiral organosilicon compounds through a Rh-catalyzed asym. 1,4-addition of arylboronic acids to β-silyl α,β-unsaturated carbonyl compounds was developed. By employing (R,R)-Bn-bod^* as a ligand, a range of arylboronic acids can be coupled with these substrates in very high enantiomeric excess. The resulting β-silyl 1,4-adducts can be converted to β-hydroxy carbonyl compounds or allylsilanes while retaining their stereochem. information. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Reference of 252288-04-3).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) 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. Trivalent phosphorus compounds called phosphines have a tetrahedral electron-group geometry which makes them structurally analogous to amines.Reference of 252288-04-3

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

On the asymmetric iridium-catalyzed N-allylation of amino acid esters: Improved selectivities through structural variation of the chiral phosphoramidite ligand was written by Albat, Dominik;Kocher, Alicia;Witt, Julia;Schmalz, Hans-Guenther. And the article was included in European Journal of Organic Chemistry in 2022.SDS of cas: 252288-04-3 This article mentions the following:

The investigation of the iridium-catalyzed asym. N-allylation of tert-Bu glycinate using a “branched” racemic 1-vinyl-alkyl Me carbonate revealed severe limitations of existing protocols. By screening a set of 24 BINOL-derived chiral phosphoramidites a new superior ligand (L24*) was identified which afforded the amination product with high enantioselectivity (≥95% ee) under optimized conditions. This ligand also allowed the N-allylation of other amino acid tert-Bu esters (derived from alanine, phenylalanine, or proline) with outstanding levels of diastereocontrol (d.r. ≥99 : 1) and negligible matched/mismatched differences. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3SDS of cas: 252288-04-3).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) 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.SDS of cas: 252288-04-3

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Asymmetric 1,4-addition of organoboron reagents to quinone monoketals catalyzed by a chiral diene/rhodium complex: a new synthetic route to enantioenriched 2-aryltetralones was written by Tokunaga, Norihito;Hayashi, Tamio. And the article was included in Advanced Synthesis & Catalysis in 2007.Application In Synthesis of (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine This article mentions the following:

A novel synthetic approach to 2-aryltetralones with high ee has been developed through asym. 1,4-addition of arylboronic acids to naphthoquinone monoketals catalyzed by a rhodium complex with the (R,R)-Ph-bod* ligand. The asym. addition proceeded in high yields with excellent enantioselectivity. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Application In Synthesis of (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. Thousands of arylphosphines have been used as chiral ligands for metal-catalyzed asymmetric reactions. Asymmetric catalytic performance is determined not only by the metal center but also by the chiral ligand selected.Application In Synthesis of (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

Amino Acid Based Phosphoramidite Ligands for the Rhodium-Catalyzed Asymmetric Hydrogenation was written by Breuil, Pierre-Alain R.;Reek, Joost N. H.. And the article was included in European Journal of Organic Chemistry in 2009.Name: (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine This article mentions the following:

Two sets of amino acid based phosphoramidite ligands with either a BINOL backbone (S_b–1a–e and R_b–1b) or a flexible biphenol backbone (2a–c and 2f) were synthesized and evaluated in the rhodium-catalyzed hydrogenation of different functionalized alkenes: di-Me itaconate (3), Me 2-acetamidoacrylate (4), Me α-acetamidocinnamate (5) and N-(3,4-dihydro-2-naphthalenyl)acetamide (6). The amino acid fragment can be modified at three positions (R¹-R³) giving rise to modular ligands. Initial experiments varying the R¹ position of the amino acid fragment, showed that the valine-based phosphoramidite ligand S_b–1b forms the most selective rhodium catalyst for three of the four substrates of the current study. The modifications at the other positions (R² and R³) tweaked the ligand structure such that enhanced selectivities were obtained; up to 97 % ee is obtained for the asym. hydrogenation of 4 with S_b–1e. For ligands with two sources of chirality match/mismatch effects are observed, the diastereoisomer S_b–1b giving higher selectivity than the diastereoisomer R_b–1b for most of the substrates. The set of phosphoramidite ligands having the flexible and cheap biphenol backbone is developed to study the ability of the amino acid derivatives as the sole source of chirality in the ligand to steer enantioselectivity in rhodium-catalyzed hydrogenation. This study shows their capacity to compete with their BINOL-based analogs and even to outclass them depending on the substrate evaluated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009). In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Name: (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. At present, the synthesis of new chiral phosphines designed specifically for nucleophilic organocatalysis remains a significant challenge. Chiral ligands coordinate to metal centers to create an asymmetric environment around the reaction centers, which eventually affects enantioselectivity and reaction rate.Name: (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis

New chiral phosphorus catalysts derived from (S)-binaphthol for highly enantioselective reduction of acetophenone by borane was written by Ma, Margaret F. P.;Li, Kangying;Zhou, Zhenghong;Tang, Chuchi;Chan, Albert S. C.. And the article was included in Tetrahedron: Asymmetry in 1999.Electric Literature of C24H22NO2P This article mentions the following:

New chiral (+)-2,2′-O,O-(1,1′-binaphthyl)-dioxo-N,N-diethylphospholidine 1 and its borane complex 3 were prepared from (S)-binaphthol and their use as catalysts in enantioselective borane reductions of prochiral acetophenone were investigated. Enantiomeric excesses of up to 98.5% have been obtained using 6 mol% of 1 at room temperature and using 6 mol% of 3 at 100°. In the experiment, the researchers used many compounds, for example, (11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3Electric Literature of C24H22NO2P).

(11bS)-N,N-Diethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine (cas: 252288-04-3) belongs to chiral phosphine ligands. The synthesis of novel trialkylphosphines can be quite difficult, thereby limiting the scope of their chiral variants. Most of these phosphines are acyclic, usually possess low nucleophilic activity, and generally display poor enantioselectivities for phosphine organocatalysis. Electric Literature of C24H22NO2P

Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis