Controlling the selectivity in cross-electrophile coupling reactions is a significant challenge, particularly when one electrophile is much more reactive. We report a general and practical strategy to address this problem in the reaction between reactive and unreactive electrophiles by a combination of nickel and Lewis acid catalysis. This strategy is used for the coupling of aryl halides with ...

COP-Cl catalyzes the rearrangement of (E)-allylic trichloroacetimidates to provide transposed allylic trichloroacetamides of high enantiopurity, a transformation that underlies the first truly practical method for transforming prochiral allylic alcohols to enantioenriched allylic amines and congeners. The high functional group compatibility of this asymmetric rearrangement and the demonstrated ...

Enantioselective allylic substitution catalyzed by transitionmetal complexes is an important process in organic synthesis. For many years, mainly palladium complexes that contain chiral ligands have been employed as efficient catalysts in these reactions. Recent studies have demonstrated that chiral catalysts based on other transition metals show different regioselectivity in the synthesis of b...

α,α-Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti-Z-selectivity (>20:1). The scope of the reaction includes both acyclic and cyclic allylic boronic esters which lead to acyclic and exocyclic tetrasubstituted homoallylic alcohols. The use of β-borylated allylic boroni...

AbstracL A selective and efficient protocol for the catalytic asymmetric cyclopropanation of allylic alcohols has been developed. The reaction involves preformation of the ethylzinc alkoxide of the alcohol and reaction with the FurukawdSimmons-Smith reagent. Zinc iodide has been shown to have a beneficial effect on the rate and enantioselectivity of the reaction. The structural variability in t...

Substituted homoallylic alcohols have been synthesised both by [2,3]-Wittig rearrangement of unsymmetrical bis-allylic ethers and reaction of alkenyl chloromethyl oxiranes with Mg/THF. These substrates were then oxidized using four different oxidants. When the substituted homoallylic alcohols were oxidized with pyridinium chlorochromate or zinc chlorochromate nonahydrate the corresponding carbo...

The scope of the triphenylsilyl perrhennate (O3ReOSiPh3, 1) catalyzed 1,3-isomerization of allylic alcohols has been thoroughly explored. It was found to be effective for a wide variety of secondary and tertiary allylic alcohol substrates bearing aryl, alkyl, and cyano substituents. Two general reaction types were found which gave high levels of product selectivity: those driven by formation of...

The addition of dialkylzincs to aldehydes is one of the most widely studied carbon-carbon bond-forming reactions. Many systems reported to date use amino alcohols as ligands and zinc complexes as catalysts.1 The asymmetric version of this alkylation reaction can also be catalyzed by chiral titanate complexes2-4 (e.g., TADDOLs2 and chiral sulfonamides3). We have recently studied a titanate compl...

Under the influence of a chiral palladium catalyst, 1,1-bis(pinacolboronate) esters undergo asymmetric cross-coupling with bromoalkenes to generate nonracemic allyl boronates with high levels of enantioselectivity. The so-formed allyl boronates may be oxidized with hydrogen peroxide to provide secondary allylic alcohols or with nitrosobenzene to furnish nonracemic tertiary allylic alcohols. Mec...

β-Lithiooxyphosphonium ylides, made in situ from an aldehyde and methylenetriphenylphosphorane, react with a second aldehyde to form E-allylic alcohols. α-Branching and α,β-unsaturation in the second aldehyde, together with the lack of further substitution on the phosphorane carbon play important roles in selectivity. A range of these aldehydes, in addition to aromatic aldehydes as the second a...