Cu
II
/TEMPO‐Catalyzed Enantioselective C(sp
3
)–H Alkynylation of Tertiary Cyclic Amines through Shono‐Type Oxidation
摘要:
AbstractA novel strategy for asymmetric Shono‐type oxidative cross‐coupling has been developed by merging copper catalysis and electrochemistry, affording C1‐alkynylated tetrahydroisoquinolines with good to excellent enantioselectivity. The use of TEMPO as a co‐catalytic redox mediator is crucial not only for oxidizing a tetrahydroisoquinoline to an iminium ion species but also for decreasing the oxidation potential of the reaction. A novel bisoxazoline ligand is also reported.
Synthesis and Electrochemical Properties of [2]Rotaxanes with <i>meta</i>-Terphenyl and <i>meta</i>-Terphenyl-Capped Dendritic Stoppers
作者:Perumal Rajakumar、Kannupal Srinivasan
DOI:10.1055/s-2005-872104
日期:——
A meta-terphenyl moiety has been employed as a stopper in a Stoddart-type [2]rotaxane, which is formed in a remarkably high yield due to the additional templating effect of the stoppers. Making use of the recognition between bis(pyridinium)ethane and dibenzo-24-crown-8 ether, the [2]rotaxanes with m-terphenyl and m-terphenyl-capped dendritic stoppers have been synthesized by a threading procedure. The [2]rotaxane 7 displays two bielectronic redox waves while the [2]rotaxanes 10 and 11 show four distinct monoelectronic redox waves.
S-BINOL based chiral dendrimers with m-terphenyl at the surface and triazole as the bridgingunit have been synthesized by a convergent synthetic strategy through the ‘click’ chemistry approach. The resazurin reduction assay method shows that all the dendrimers exhibit antibacterial activity against Shigella dysenteriae, Staphylococcus aureus and Serratia marcescen. Dendrimer 2 shows better inhibitory
Asymmetricsynthesis: A class of cinchona alkaloid-derived zwitterions has been successfully applied to highly enantioselective Steglich rearrangement of oxindoles. The same catalytic system is also applicable in the asymmetric aldol reaction of oxindoles. This finding paves the way to the development of new reaction protocols exploiting cinchona alkaloid-derived zwitterions as asymmetric nucleophilic