- Divergent regioselectivity in the synthesis of trisubstituted allylic alcohols by nickel- and ruthenium-catalyzed alkyne hydrohydroxymethylation with formaldehyde
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Stoichiometric metals banned: Nonsymmetrically disubstituted alkynes were converted into primary trisubstituted allylic alcohols upon exposure to paraformaldehyde in the presence of nickel or ruthenium catalysts, which exhibit complementary regioselectivity and complete stereoselectivity in the absence of exogenous reducing agents (see scheme). Copyright
- Bausch, Cory C.,Patman, Ryan L.,Breit, Bernhard,Krische, Michael J.
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supporting information; experimental part
p. 5687 - 5690
(2011/08/06)
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- Vanadium-catalyzed asymmetric epoxidation of allylic alcohols in water
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Asymmetric V-catalyzed epoxidation of allylic alcohols can be carried out in water with chiral ligands, which incorporate sulfonamide and hydroxamic acid fragments. Furthermore, the reaction, notorious for its ligand-deceleration effect, in water turned into the ligand-accelerated process. By using this aqueous protocol, a range of allylic alcohols were epoxidized with up to 94% ee.
- Malkov, Andrei V.,Czemerys, Louise,Malyshev, Denis A.
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supporting information; experimental part
p. 3350 - 3355
(2009/09/26)
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- Arylation of allyl alcohols in organic and aqueous media catalyzed by oxime-derived palladacycles: Synthesis of β-arylated carbonyl compounds
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A 4-hydroxyacetophenone oxime-derived palladacycle catalyzes the Mizoroki-Heck reaction of allyl alcohols with aryl iodides, bromides, and chlorides in aqueous and organic solvents. The reaction takes place in the presence of dicyclohexylmethylamine or cesium carbonate as bases, the addition of tetrabutylammonium bromide (TBAB) as additive for aryl bromides and chlorides being necessary. Under these reaction conditions, β-arylated aldehydes and ketones are mainly obtained using a rather low loading of palladium (0.1-1 mol%). Similar catalytic activity is shown by a Kaiser oxime resin-derived palladacycle, which allows one to perform recycling and reusing experiments with low Pd leaching. The high regio- and chemoselectivity observed supported that these palladacycles, working as a source of Pd(0) species, operates mainly through a neutral mechanism. This methodology has been applied to the synthesis of important β-arylated carbonyl compounds, such as 4-phenylbutan-2-one, 4-(4-hydroxyphenyl)butan-2-one, dihydrochalcones, the anti-inflamatory nabumetone, and the fragance β-lilial. γ-Arylation is observed in the reactions of allyl alcohol and but-3-en-2-ol with 2-iodoaniline giving mainly the corresponding quinolines. The same tendency is observed in the case of 1,1-dimethylallyl alcohol affording either γ-arylated alcohols or (E)-1-arylisoprenes.
- Alacid, Emilio,Najera, Carmen
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p. 2572 - 2584
(2008/09/19)
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- Intramolecular syn and anti hydrosilylation and silicon-assisted cross-coupling: highly regio- and stereoselective synthesis of trisubstituted allylic alcohols.
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[reaction: see text] The geometrical isomers of 6-ethylidenedioxadisilacyclohexane were prepared by intramolecular hydrosilylation of an unsymmetrical disiloxane by the use of Pt (syn) and Ru (anti) catalysts. This new class organosilicon reagents underwent cross-coupling reactions with a range of aryl iodides to afford (E)- and (Z)-trisubstituted allylic alcohols in a highly stereospecific fashion.
- Denmark, Scott E,Pan, Weitao
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p. 1119 - 1122
(2007/10/03)
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- Stille coupling versus cine substitution. Electronic effects also influence coupling sterically hindered stannanes
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Very low ligand to palladium ratios, especially weak ligands and iodides as electrophiles allow Stille couplings to very hindered stannanes, not possible under common conditions. In contrast, the usage of triflates and elevated temperatures yields exclusi
- Flohr, Alexander
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p. 5177 - 5180
(2007/10/03)
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- Regio- and Stereoselective Hydrosulfonylation of Conjugated Dienes via a (?-Allyl)palladium Complex
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The combination of a sulfonylpalladation of acyclic dienes 1 (with 2 equiv of NaSO2R and 1 equiv of PdCl2 in acetic acid or acetic acid-H2O at 50-80 deg C under air) and a protiodepalladation of the thus obtained palladium complexes 3 with dimethylglyoxime (in a protic solvent at room temperature) provides di- and trisubstituted (Z)-Δ3-sulfones 12 selectively, irrespective of the stereochemistry of the starting dienes.Similar treatment of 1-vinylcycloalkenes 5 (n (1,3) strain between Pd and the substituent on the allylic position.
- Tamaru, Yoshinao,Yamada, Yoshimi,Kagotani, Masahiro,Ochiai, Hirofumi,Nakajo, Eiji,et al.
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p. 4669 - 4681
(2007/10/02)
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