Enantioselective cross-electrophile
reactions remain a challenging
subject in metal catalysis, and with respect to data, studies have
mainly focused on stereoconvergent reactions of racemic alkyl electrophiles.
Here, we report an enantioselective cross-electrophile aryl-alkenylation
reaction of unactivated alkenes. This method provides access to a
number of biologically important chiral molecules such as dihydrobenzofurans,
indolines, and indanes. The incorporated alkenyl group is suitable
for further reactions that can lead to an increase in molecular diversity
and complexity. The reaction proceeds under mild conditions at room
temperature, and an easily accessible chiral pyrox ligand is used
to afford products with high enantioselectivity. The synthetic utility
of this method is demonstrated by enabling the modification of complex
molecules such as peptides, indometacin, and steroids.
Catalytic asymmetric dicarbofunctionalization of tethered alkenes has emerged as a promising tool for producing chiral cyclic molecules; however, it typically relies on aryl-tethered alkenes to form benzene-fused compounds. Herein, we report an enantioselective cross-electrophile divinylation reaction of nonaromatic substrates, 2-bromo-1,6-dienes. The approach thus offers a route to new chiral cyclic architectures, which are key structural motifs found in various biologically active compounds. The reaction proceeds under mild conditions, and the use of chiral t-Bu-pmrox and 3,5-difluoro-pyrox ligands resulted in the formation of divinylated products with high chemo-, regio-, and enantioselectivity. The method is applicable for the incorporation of chiral hetero-and carbocycles into complex molecules.
The chiral Cu-complex-catalyzed intramolecular interception of meso-α,α'-diazido alcohols with aryldiazoacetates is explored. Most of the enantioenriched α-imino esters with three continuous stereocenters are produced with good to excellent yield and enantioselectivity, and a chiral pocket model is proposed for rationalization of the asymmetric desymmetrization.
Intramolecular Schmidt reaction of acyl chlorides with alkyl azides through N-acyliminium ion intermediates is designed and realized. The intramolecular capture of the intermediates with aromatic rings affords several nitrogen-containing tricyclic skeletons. The important feature of the domino process is the efficiency in bond reorganization and ring formation.
Allylboronates are unique building blocks widely used in organic synthesis, but the construction of cyclic allylboranates remains a challenging subject. We demonstrate here a mild and efficient access to this type of compound through the cross-electrophile coupling of vinyl triflates and α-chloroboronates. The reaction proceeded with a good substrate scope and good functional group compatibility. The ready availability of vinyl triflates from ketones, as well as the rich chemistry of allylboranates, makes our method suitable for the divergent modification of biologically active compounds. Preliminary mechanistic studies revealed that α-chloroboronates were activated via a radical process.
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