3 research outputs found
Silver(I)-Catalyzed Diastereoselective Hydroborylation of Cyclopropenes
An effective (NHC)AgCl catalysis was developed in the
hydroborylation
of cyclopropenes with B2pin2, delivering a variety
of cyclopylboronates in a stereoselective manner, which could be easily
transformed for the construction of versatile cyclopropanes. This
protocol works effectively under mild reaction conditions in an open-air
atmosphere, and it was easy to apply on a gram scale. This novel method
in detail was also explored by control experiments, providing a number
of key insights. The kinetic process followed by 1H NMR
indicated that the reaction was finished in 15 min. Furthermore, the
mechanism of silver(I)-catalyzed hydroborylation of cyclopropenes
was proposed, with the protonation by methanol as the rate-determining
step
Rapid Access to Chiral Spiro[2.3] Lactams: Stereoselective Hydroborylation and Hydrosilylation and Remote Control of Axial Chirality by Copper-Catalyzed Desymmetrization of Spirocyclopropenes
Chiral spirocyclopropyl β-lactams are common motifs
in bioactive
compounds and pharmaceuticals. Here we disclose a diastereoselective
and enantioselective hydroborylation and hydrosilylation of spirocyclopropenes,
via a Cu-catalyzed desymmetrization strategy, for the rapid preparation
of enantio-enriched spirocyclopropyl β-lactams. The efficient
desymmetrization strategy allows the remote control of axial chirality,
offering the borylated and silylated products bearing central, spiro,
and axial chirality. The combination of multichiral elements would
provide a novel motif for biological evaluation in potential drug
discovery
Ligand-Controlled Inversion of Diastereo- and Enantioselectivity in Silver-Catalyzed Azomethine Ylide–Imine Cycloaddition of Glycine Aldimino Esters with Imines
A highly
diastereo- and enantioselective silver-catalyzed azomethine
ylide–imine (AYI) cycloaddition reaction of glycine aldimino
esters with imines was developed in which the Xing-Phos-controlled <i>syn</i>-selective or DTBM-Segphos-induced <i>anti</i>-selective AYI cycloaddition reaction could be applied to the synthesis
of a variety of stereodivergent 1-alkyl-2,5-substituted imidazolidines
with high yields and excellent enantioselectivities (up to 99% ee)
as well as good diastereoselectivities (up to 99:1 dr) under mild
reaction conditions