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Cycloadditions chiral

Keywords carbonyl compounds, chiral dienophiles, chiral dienes, chiral catalysts, intramolecular cycloadditions, chiral Lewis acids... [Pg.312]

Togni A., Pastor S. D. Cooperativity of Chirality in Homogeneous Catalysis The Gold(I)-Catalyzed Aldol Reaction and the Vanadium(IV)-Catalyzed Hetero-Diels-Alder Cycloaddition Chirality 1991 3 331-340... [Pg.323]

In the area of [3 + 2]-cycloadditions (1,3-dipolar cycloadditions), chiral silver catalysts have been utilized extensively for the enantioselective formation of five-membered rings from prochiral substrates. For example, Zhang and co-workers360 have reported the highly enantioselective Ag(i)-catalyzed [3 + 2]-cycloaddition of azomethine ylides to electron-deficient alkenes. Thus, reaction of ct-imino esters 442 with dimethyl maleate in the presence of catalytic amounts of silver(i) acetate and the chiral bisferrocenyl amide phosphine 443 provided the chiral pyrrolidines 444 with high stereoselectivities and chemical yields (Scheme 131). Only the endo-products were isolated in all cases. [Pg.566]

Vasella, A, Stereoselektivitat und Reaktivitat bei der 1,3-dipolaren Cycloaddition chiraler N-(Alkoxyalkyl)nitrone, Helv. Chim. Acta, 60, 1273-1294, 1977. [Pg.496]

Asymmetric dipolar cycloadditions. Chiral pyrazolines are accessible through 1,3-dipolar cycloaddition of trimethylsilyidiazomethane to (V-(2-alkenoyl)borane-10-2-sultams. [Pg.405]

Dipoles are the three-atom components of [3+2]-cydoadditions. These are 4n electrons species, so [3+2]-cycloadditions are thermally allowed according to the rules of orbital symmetry [624g], The interactions between the frontier orbitals of the two partners are of prime importance, and concerted reactions take place in a supra-suprafacial fashion. When the 1,3-dipoles are not symmetrical, their reactions with unsymmetrical dipolarophiles may give regioisomers. Lack of regioselectivity limits some types of cycloadditions. Chirality can be introduced other on the dipole or on the dipolarophile. [Pg.526]

Intramolecular versions of the ene reaction using Lewis acids can be applied to nonconjugated dienes. Thus, 2.8-dienoic acid derivatives lead to cyclohexane systems27. Side products in this conversion stem from intramolecular hetero-Diels-Alder cycloaddition. Chiral Lewis acids, such as titanium alkoxidcs modified with tartaric acid derived chiral diols, lead to asymmetric induction with up to 98% ee27,88. [Pg.403]

Induced Diastereoselection in Nitrone Cycloadditions Chiral Nitrones... [Pg.755]


See other pages where Cycloadditions chiral is mentioned: [Pg.1489]    [Pg.538]   
See also in sourсe #XX -- [ Pg.115 ]




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1.3- Dipolar cycloaddition of chiral nitrones

1.3- Dipolar cycloadditions chiral auxiliaries

Addition patterns, chiral cycloaddition reactions

Carbohydrate nitroalkenes chiral, cycloaddition

Chiral auxiliaries tandem cycloaddition

Chiral auxiliaries, diastereoselectivity, asymmetric cycloadditions

Chiral auxiliaries, diastereoselectivity, asymmetric intramolecular cycloadditions

Chiral auxiliaries, diastereoselectivity, asymmetric nitrile oxide cycloadditions

Chiral auxiliary cycloaddition

Chiral cycloaddition reactions

Chiral dienophiles cycloaddition

Chiral enamides, cycloaddition

Chiral enamines cycloaddition

Chiral imine 2+2] cycloaddition

Chiral metal complexes cycloaddition

Chiral nitrones 1,3-dipolar cycloaddition

Cycloaddition chiral nitrones

Cycloaddition reactions chiral cyclobutanones

Cycloaddition reactions chiral dipolarophiles

Cycloaddition reactions chiral sulfinyl groups

Cycloadditions chiral auxiliary

Cycloadditions chiral catalysts

Cycloadditions chiral phosphoric acids

Cycloadditions with chiral templates

Diastereoselective cycloaddition chiral auxiliaries

Diisopropyl nitrile oxide cycloadditions, chiral

Dipolar Cycloaddition of Chiral N-(Alkoxyalkyl) Nitrones

Dipolarophiles asymmetric cycloaddition reactions, chiral

Intermolecular cycloadditions achiral nitrile oxides/chiral olefins

Photochemical cycloadditions, chiral auxiliaries

Sugars cycloadditions, chiral auxiliaries

Sulfoxide, chiral vinyl 3 + 2] cycloaddition reactions

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