Asymmetric Total Synthesis of Lepadiformine C Using Memory of Chirality in an Intramolecular Ester Enolate Michael Addition
作者:Seokwoo Lee、Minsik Bae、Jinkyung In、Jae Hyun Kim、Sanghee Kim
DOI:10.1021/acs.orglett.6b03550
日期:2017.1.6
The asymmetric synthesis of lepadiformine C was achieved using d-proline as the only chiral source. The synthetic strategy features the use of the principle of “memory of chirality” in an intramolecular Michael addition to construct the bicyclic intermediate without the aid of external chiral sources. A brief mechanistic rationale is presented to account for the stereochemical outcome.
Gold-Catalyzed Highly Enantioselective Synthesis of Axially Chiral Allenes
作者:Vanessa Kar-Yan Lo、Man-Kin Wong、Chi-Ming Che
DOI:10.1021/ol702970r
日期:2008.2.1
Axiallychiral allenes are synthesized from chiral propargylamines catalyzed by KAuCl4 in high yields (up to 93% yield) and excellent enantioselectivities (up to 97% ee) in CH3CN at 40 degrees C. The reaction has been applied to the synthesis of novel allene-modified artemisinin derivatives with the delicate endoperoxide moieties remaining intact. A tentative mechanism regarding gold(I)-catalyzed intramolecular
Reactivity and Selectivity of Charged Phenyl Radicals toward Amino Acids in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer
作者:George O. Pates、Leonard Guler、John J. Nash、Hilkka I. Kenttämaa
DOI:10.1021/ja111280t
日期:2011.6.22
a hydrogenatom from the α-carbon is only preferred for glycine; for the other amino acids, a hydrogenatom is preferentially abstracted from the side chain. The electrophilicity of the radicals does not appear to have a major influence on the site from which the hydrogenatom is abstracted. Hence, the regioselectivity of hydrogenatomabstraction appears to be independent of the structure of the radical