Titanium(salalen) complex 1 was an effective catalyst for asymmetric epoxidation of enol esters. Although (E)-enol esters were reluctant to proceed, (Z)-enol esters underwent asymmetric epoxidation to give the epoxides in high yields with high enantioselectivity ranging from 86 to >99% ee in the presence of aqueous hydrogenperoxide as the stoichiometric oxidant. Complete enantioselectivity was observed
Rhodium-Catalyzed Selective <i>anti</i>-Markovnikov Addition of Carboxylic Acids to Alkynes
作者:Alexandre Lumbroso、Nicolas R. Vautravers、Bernhard Breit
DOI:10.1021/ol102365e
日期:2010.12.3
The selective intermolecular anti-Markovnikov addition of carboxylic acids to terminal alkynes yielding valuable Z-enol esters has been achieved for the first time under rhodium-catalyzed conditions. The catalyst system is applicable to a broad substrate scope and displays a wide functional group tolerance.