46 research outputs found
Enantioselective C-H Crotylation of Primary Alcohols via Hydrohydroxyalkylation of Butadiene
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Direct, Redox-Neutral Prenylation and Geranylation of Secondary Carbinol C–H Bonds: C4-Regioselectivity in Ruthenium-Catalyzed C–C Couplings of Dienes to α‑Hydroxy Esters
No full textThe ruthenium catalyst generated <i>in situ</i> from
Ru<sub>3</sub>(CO)<sub>12</sub> and tricyclohexylphosphine, PCy<sub>3</sub>, promotes the redox-neutral C–C coupling of aryl-substituted
α-hydroxy esters to isoprene and myrcene at the diene C4-position,
resulting in direct carbinol C–H prenylation and geranylation,
respectively. This process enables direct conversion of secondary
to tertiary alcohols in the absence of stoichiometric byproducts or
premetalated reagents, and is the first example of C4-regioselectivity
in catalytic C–C couplings of 2-substituted dienes to carbonyl
partners. Mechanistic studies corroborate a catalytic cycle involving
diene–carbonyl oxidative coupling
Regioselective Ruthenium Catalyzed Hydrohydroxyalkylation of Dienes with 3-Hydroxy-2-oxindoles: Prenylation, Geranylation, and Beyond
No full textAmphiphilic π‑Allyliridium <i>C</i>,<i>O</i>‑Benzoates Enable Regio- and Enantioselective Amination of Branched Allylic Acetates Bearing Linear Alkyl Groups
No full textThe first examples of amphiphilic
reactivity in the context of
enantioÂselective catalysis are described. Commercially available
Ï€-allyliridium <i>C</i>,<i>O</i>-benzoates, which are stable to air,
water and SiO<sub>2</sub> chromatography, and are well-known to catalyze
allyl acetate-mediated carbonyl allylation, are now shown to catalyze
highly chemo-, regio- and enantioÂselective substitutions of
branched allylic acetates bearing linear alkyl groups with primary
amines
Redox-Triggered C–C Coupling of Alcohols and Vinyl Epoxides: Diastereo- and Enantioselective Formation of All-Carbon Quaternary Centers via tert
No full textRuthenium-Catalyzed Hydrohydroxyalkylation of Acrylates with Diols and α-Hydroxycarbonyl Compounds To Form Spiro- and α-Methylene-γ-butyrolactones
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Amplification of Anti-Diastereoselectivity via Curtin−Hammett Effects in Ruthenium-Catalyzed Hydrohydroxyalkylation of 1,1-Disubstituted Allenes: Diastereoselective Formation of All-Carbon Quaternary Centers
No full textHydroamination versus Allylic Amination in Iridium-Catalyzed Reactions of Allylic Acetates with Amines: 1,3-Aminoalcohols via Ester-Directed Regioselectivity
No full textIn the presence of a neutral dppf-modified
iridium catalyst and
Cs<sub>2</sub>CO<sub>3</sub>, linear allylic acetates react with primary
amines to form products of hydroamination with complete 1,3-regioselectivity.
The collective data, including deuterium labeling studies, corroborate
a catalytic mechanism involving rapid, reversible acetate-directed
aminoiridation with inner-sphere/outer-sphere crossover followed by
turnover-limiting proto-demetalation mediated by amine
