130 research outputs found
Divergent regioselectivity in photoredox-catalyzed hydrofunctionalization reactions of unsaturated amides and thioamides
A direct method to construct 2-oxazolines and 2-thiazolines from corresponding allylic amides and thioamides is reported
Reversing the Regioselectivity of Halofunctionalization Reactions through Cooperative Photoredox and Copper Catalysis
Halofunctionalization of alkenes is a classical method for olefin difunctionalization. It gives rise to adducts which are found in many natural products and biologically active molecules, and offers a synthetic handle for further manipulation. Classically, this reaction is performed with an electrophilic halogen source and leads to regioselective formation of the halofunctionalized adducts. Herein, we demonstrate a reversal of the native regioselectivity for alkene halofunctionalization through the use of an acridinium photooxidant in conjunction with a copper cocatalyst
Self-Consistent Synthesis of the Squalene Synthase Inhibitor Zaragozic Acid C via Controlled Oligomerization
Despite the prevalence of repeating subunits in chiral natural products, stereocontrolled oligomerization is a largely unexplored strategy for construction of carbon skeletal frameworks. This report describes the use of silyl glyoxylates as dipolar glycolic acid synthons in a controlled oligomerization reaction for the efficient construction of the squalene synthase inhibitor zaragozic acid C. This new methodology allows rapid, stereocontrolled formation of the carbon skeleton with a desirable protecting group scheme while minimizing functional group repair and oxidation state manipulations
Solid-State Characterization and Photoinduced Intramolecular Electron Transfer in a Nanoconfined Octacationic Homo[2]Catenane
Hydrodecarboxylation of Carboxylic and Malonic Acid Derivatives via Organic Photoredox Catalysis: Substrate Scope and Mechanistic Insight
A direct, catalytic hydrodecarboxylation
of primary, secondary,
and tertiary carboxylic acids is reported. The catalytic system consists
of a Fukuzumi acridinium photooxidant with phenyldisulfide acting
as a redox-active cocatalyst. Substoichiometric quantities of HuÌnigâs
base are used to reveal the carboxylate. Use of trifluoroethanol as
a solvent allowed for significant improvements in substrate compatibilities,
as the method reported is not limited to carboxylic acids bearing
α heteroatoms or phenyl substitution. This method has been applied
to the direct double decarboxylation of malonic acid derivatives,
which allows for the convenient use of dimethyl malonate as a methylene
synthon. Kinetic analysis of the reaction is presented showing a lack
of a kinetic isotope effect when generating deuterothiophenol in situ
as a hydrogen atom donor. Further kinetic analysis demonstrated first-order
kinetics with respect to the carboxylate, while the reaction is zero-order
in acridinium catalyst, consistent with another finding suggesting
the reaction is light limiting and carboxylate oxidation is likely
turnover limiting. SternâVolmer analysis was carried out in
order to determine the efficiency for the carboxylates to quench the
acridinium excited state
Hydrodecarboxylation of Carboxylic and Malonic Acid Derivatives via Organic Photoredox Catalysis: Substrate Scope and Mechanistic Insight
A direct, catalytic hydrodecarboxylation
of primary, secondary,
and tertiary carboxylic acids is reported. The catalytic system consists
of a Fukuzumi acridinium photooxidant with phenyldisulfide acting
as a redox-active cocatalyst. Substoichiometric quantities of HuÌnigâs
base are used to reveal the carboxylate. Use of trifluoroethanol as
a solvent allowed for significant improvements in substrate compatibilities,
as the method reported is not limited to carboxylic acids bearing
α heteroatoms or phenyl substitution. This method has been applied
to the direct double decarboxylation of malonic acid derivatives,
which allows for the convenient use of dimethyl malonate as a methylene
synthon. Kinetic analysis of the reaction is presented showing a lack
of a kinetic isotope effect when generating deuterothiophenol in situ
as a hydrogen atom donor. Further kinetic analysis demonstrated first-order
kinetics with respect to the carboxylate, while the reaction is zero-order
in acridinium catalyst, consistent with another finding suggesting
the reaction is light limiting and carboxylate oxidation is likely
turnover limiting. SternâVolmer analysis was carried out in
order to determine the efficiency for the carboxylates to quench the
acridinium excited state
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