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Arylation Rh-catalyzed

C-H/C-M Arene Arylation (Rh-Catalyzed Oxidative Coupling Methods). 259... [Pg.231]

Scheme 8 Aryl-Rh-catalyzed addition/p-C elimination of cyclobutanones... Scheme 8 Aryl-Rh-catalyzed addition/p-C elimination of cyclobutanones...
Cationic phosphine ligands containing guanidiniumphenyl moieties were originally developed in order to make use of their pronounced solubility in water [72, 73]. They were shown to form active catalytic systems in Pd-mediated C-C coupling reactions between aryl iodides and alkynes (Castro-Stephens-Sonogashira reaction) [72, 74] and Rh-catalyzed hydroformylation of olefins in aqueous two-phase systems [75]. [Pg.237]

Aryl furans were prepared in moderate yields by Rh-catalyzed regioselective hydroformylation of substituted propargylic alcohols followed by cyclization, and an example is shown below <06ASC545>. [Pg.184]

Rh-catalyzed hydrogenation of simple enamides has attracted much attention recently. With the development of increasingly efficient chiral phosphorus ligands, extremely high ee-values can be obtained in the Rh-catalyzed hydrogenation of a-aryl enamides. E/Z-isomeric mixtures of -substituted enamides can also be hydrogenated, with excellent ee-values. Some efficient examples (>95% ee) of hydrogenation of a-phenylenamide and E/Z-isomeric mixtures of / -methyl-a-phenylenamide are listed in Table 26.3. [Pg.866]

Jiang et al.4 have recently succeeded in hydrogenating both aryl alkyl and dialkyl ketones. High enantioselectivity was obtained using PennPhos (19)-coordinated Rh complex as the catalyst. This success is based on the finding that a weak base (such as 2,6-lutidine) can facilitate the Rh-catalyzed hydrogenation of simple ketones (Scheme 6 35). [Pg.364]

The coupling of chiral amines with aryl bromides proceeds without racemization by proper choice of ligands. Intermolecular animation of a chiral amine proceeds without loss of enantiomeric purity with Pd(0)-(o-Tol)3P. Synthesis of the optically pure indole 415, an intermediate for the synthesis of a potent ACE inhibitor, has been achieved by the Pd-catalyzed amination of 414, which is prepared by the Heck reaction of bromide 413 and Rh-catalyzed aymmetric hydrogenation [205],... [Pg.81]

Fig. 20 Conversion curves for the Rh-catalyzed hydrogenation of Z-methyl-a-acetamido-cinnamate using ligands bearing the backfolded poly(aryl ether) dendrons displayed in Fig. 19. (B-Gx) compared with that of the third-generation catalyst displayed in Fig. 17 (G3) [48]... Fig. 20 Conversion curves for the Rh-catalyzed hydrogenation of Z-methyl-a-acetamido-cinnamate using ligands bearing the backfolded poly(aryl ether) dendrons displayed in Fig. 19. (B-Gx) compared with that of the third-generation catalyst displayed in Fig. 17 (G3) [48]...
Brunner and Fiirst[431 reported the synthesis of a series of optically active, extended chelate phosphines, one of which was derived from the reaction of 5-bromo-l,3-di(bor-neoxymethyl)benzene (69) and bis(dichlorophosphino)methane (70). Technically, the product (-)-l,l-bis 3, 5 -di(borneoxymethyl)phenyl]phosphino methane (71) is both a first tier P- and 1,3-aryl-branched dendrimer. Excluding distortions, the maximum distance between the P atom and the most distant H atom(s) is 11.9 A for the two-layer ligand 71. The Rh-catalyzed [Rh(cod)Cl]2) hydrogenation of (a)-/V-acetamidocinnamic acid in the presence of 71 afforded a disappointingly low [5.2 % ee (/ )] optical induction. [Pg.198]

A rhodium(l)-catalyzed system in THF is also effective in the Mizoroki-Heck-type reaction of arylsilanediols with acrylates (Scheme 4).53 Interestingly, the use of aqueous THF switches the reaction to 1,4-addition forming /3-arylated esters. The proposed catalytic cycles for these reactions involve 1,4-addition of an arylrhodium species to an acrylate. The change of the reaction pathway is probably because, in aqueous THF, the resultant Rh enolate 6 undergoes protonolysis rather than /3-elimination. Similar Rh-catalyzed 1,4-additions to a,/3-unsaturated carbonyl compounds have been achieved with arylsilicones,54 arylchlorosilanes,55 and aryltrialkoxysilanes.56,57 The use of a cationic Rh-binap complex leads to highly enantioselective 1,4-additions of alkenyl- and arylsilanes.58 583... [Pg.302]

Iridium complexes as well as [Rh(OH)(cod)]2 can catalyze the Mizoroki-Heck-type reaction of arylsilanediols with acrylates. Aryltrialkoxysilanes activated by TBAF also work as the aryl donor in the presence of H20. In contrast to the Rh-catalyzed reaction, this reaction does not form / -arylated saturated esters even in aqueous media.69... [Pg.304]

The optically active (A)-(+)- and (i )-(—)-2,2 -bis[diarylstibano]-l,l -binaphthyls (BINASb) have been prepared and used as chiral auxiliaries in the Rh-catalyzed asymmetric hydrosilylation of ketones with diphenylsilane.49,49a When acetophenone is reduced using 0.25 mol% of [Rh(COD)Cl]2 as the catalyst and 0.5 mol% of (i )-BINASb (aryl = />-tolyl) as the ligand, (i )-l-phenylethanol is formed in 78% yield and in 32% ee (Equation (15)). When (i )-BINAP is used as the chiral ligand instead of (i )-BINASb, the yield and enantiomeric excess of (7 )-l-phenylethanol are 42% and 0.6%, respectively. [Pg.429]

Note The Rh-catalyzed C-acylation of reduced pyrazines with carbon monoxide and ethylene appears to offer considerable potential for further development. l-Methyl-4-(pyridin-2-yl)piperazine (292) gave l-methyl-3-propionyl-4-(pyridin-2-yl)-l,4,5,6-tetrahydropyrazine (293) [Rh4(CO)12, PhMe, H2C=CH2 J, to 10 atm, CO l to 15 atm, 25°C, autoclave then 160°C, 20 h 85%] several N-alkyl/aryl homologues were made similarly.1404... [Pg.343]

Table 2. Asymmetric hydrosilylation of alkyl aryl ketones catalyzed by Rh(I)-(2)... Table 2. Asymmetric hydrosilylation of alkyl aryl ketones catalyzed by Rh(I)-(2)...
Other Applications. In the reactions discussed so far, methylenebis(oxazolines) were found to be superior to bioxazo-lines of type (4). However, there are some enantioselective metal-catalyzed processes for which the bioxazolines (4) are better suited than neutral or anionic methylenebis(oxazolines). Two examples, the Ir-catalyzed transfer hydrogenation of aryl alkyl ketones and the Rh-catalyzed hydrosilylation of acetophenone, are given in eq 10 and eq 11. [Pg.272]

The Rh-catalyzed reaction of aryl- and vinylsilanediols with internal alkynes in aqueous solvent gives hydroarylation and hydrovinylation products, respectively (Scheme 10.216) [561]. It has been proposed that this reaction occurs via carborho-dation of an aryl- or vinylrhodium intermediate to an alkyne then protonation with the silanediol. Arylation and vinylation of aromatic aldehydes with organosilicon reagents can also be achieved in Rh-catalyzed systems (Scheme 10.216) [560, 562]. [Pg.540]


See other pages where Arylation Rh-catalyzed is mentioned: [Pg.231]    [Pg.235]    [Pg.231]    [Pg.235]    [Pg.163]    [Pg.174]    [Pg.7]    [Pg.9]    [Pg.12]    [Pg.26]    [Pg.27]    [Pg.32]    [Pg.784]    [Pg.784]    [Pg.809]    [Pg.817]    [Pg.860]    [Pg.919]    [Pg.925]    [Pg.1137]    [Pg.536]    [Pg.38]    [Pg.15]    [Pg.911]    [Pg.1092]    [Pg.413]    [Pg.1062]    [Pg.1068]    [Pg.334]    [Pg.572]    [Pg.86]   
See also in sourсe #XX -- [ Pg.86 ]




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