The first enantioselective construction of a new class of axially chiral naphthyl-indole skeletons has been established by organocatalytic asymmetric coupling reactions of 2-naphthols with 2-indolylmethanols (up to 99 % yield, 97:3 e.r.). This approach not only affords a new type of axially chiral heterobiaryl backbone, but also provides a new catalytic enantioselective strategy for constructing axially chiral biaryl scaffolds by making use of the C3-electrophilicity of 2-indolylmethanols.
Highly regio- and
enantioselective allylic alkylation has been
achieved enabled by the merger of photoredox and palladium catalysis.
In this dual catalytic process, alkyl radicals generated from 4-alkyl-1,4-dihydropyridines
act as the coupling partners of the π-allyl palladium complexes.
The generality of this method has been illustrated through the reaction
of a variety of allyl esters with 4-alkyl-1,4-dihydropyridines. This
mechanistically novel strategy expands the scope of the traditional
Pd-catalyzed asymmetric allylic alkylation reaction and serves as
its alternative and potential complement.
Radical alkylation of imines with 4-alkyl-1,4-dihydropyridines cocatalyzed by iridium/ruthenium complex and Brønsted acid under visible light irradiation has been achieved. Both aldimines and ketimines can undergo this transformation. Common functional groups, such as hydroxyl groups, ester, amide, ether, cyanide, and heterocycles, can be tolerated in this reaction. A variety of structurally diverse amines (57 examples) have been produced with up to 98% isolated yields using this method.
The first catalytic asymmetric cycloaddition using 2-indolylmethanols as 3C building blocks has been established by a chiral phosphoric acid-catalyzed enantioselective and regioselective [3+3] cycloaddition of 2-indolylmethanols with azomethine ylides, which constructed biologically important tetrahydro-γ-carboline frameworks in high yields and excellent enantioselectivities (up to 83 % yield, 99:1 e.r.). This reaction not only represents the first application of 2-indolylmethanols as 3C building blocks in catalytic asymmetric cycloadditions, but also has established an abnormal regioselectivity in indolylmethanol-involved transformations.
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