Impact of Silyl Enol Ether Stability on Palladium-Catalyzed Arylations
作者:Yong Guo、Guo-Hong Tao、Alex Blumenfeld、Jean’ne M. Shreeve
DOI:10.1021/om1000259
日期:2010.4.12
The effect of stability on arylation of silyl enolethers as dictated by the presence of bulky silyl groups was elucidated through experiment and calculation. With the enhancement of stability of the silyl enolethers, especially of acyclic ethers, the efficiency of palladium-catalyzed arylation of silyl enolates based on ketone precursors was greatly increased.
Design, Synthesis, and Applications of Potential Substitutes of <i>t</i>-Bu-Phosphinooxazoline in Pd-Catalyzed Asymmetric Transformations and Their Use for the Improvement of the Enantioselectivity in the Pd-Catalyzed Allylation Reaction of Fluorinated Allyl Enol Carbonates
substitutes of t-Bu-PHOX in asymmetric catalysis is reported. The design relies on the incorporation of geminal substituents at C5 in combination with a substituent at C4 other than t-butyl (i-Pr, i-Bu, or s-Bu). Most of these new members of the PHOX ligand family behave similarly in terms of stereoinduction to t-Bu-PHOX in three palladium-catalyzed asymmetric transformations. Electronically modified ligands
Synthesis of α-Trifluoromethyl Ketones via the Cu-Catalyzed Trifluoromethylation of Silyl Enol Ethers Using an Electrophilic Trifluoromethylating Agent
作者:Lun Li、Qing-Yun Chen、Yong Guo
DOI:10.1021/jo500713f
日期:2014.6.6
A method has been developed for the synthesis of α-trifluoromethyl ketones via the Cu-catalyzed trifluoromethylation of silyl enol ethers with an electrophilic trifluoromethylating agent, which produces a trifluoromethyl radical.
Unexpected effect of the fluorine atom on the optimal ligand-to-palladium ratio in the enantioselective Pd-catalyzed allylation reaction of fluorinated enol carbonates
The enantioselective Pd-catalyzed allylation reaction of fluorinated allyl enol carbonates is presented; a key feature of this transformation is the important effect of the ligand-to-palladium ratio on the enantioselectivity of the α-fluoroketones, since using a ligand excess (L/Pd ratio = 1.25 : 1) led to moderate results (30–76% ee), while using a L/Pd ratio <1 : 1.67 (to as low as 1 : 4) allowed the desired products to be obtained with high enantiopurity (up to 94% ee).