Catalytic, Enantioselective α‐Alkylation of Azlactones with Nonconjugated Alkenes by Directed Nucleopalladation
作者:Sri Krishna Nimmagadda、Mingyu Liu、Malkanthi K. Karunananda、De‐Wei Gao、Omar Apolinar、Jason S. Chen、Peng Liu、Keary M. Engle
DOI:10.1002/anie.201814272
日期:2019.3.18
palladium(II)‐catalyzed enantioselective α‐alkylation of azlactones with nonconjugated alkenes is described. The reaction employs a chiral BINOL‐derived phosphoric acid as the source of stereoinduction, and a cleavable bidentate directing group appended to the alkene to control the regioselectivity and stabilize the nucleopalladated alkylpalladium(II) intermediate in the catalytic cycle. A wide range of
The enantioselective reaction of 2H-azirines with oxazol-5-(4H)-ones (oxazolones) using a cinchonaalkaloid sulfonamide catalyst has been developed. The reaction proceeded at the C-2 position of oxazolones to afford products with consecutive tetrasubstituted stereogenic centers in high yield with high diastereo- and enantioselectivity. The obtained aziridines were converted into various chiral compounds
Highly Stereoselective [4+2] Cycloaddition of Azlactones to β,γ-Unsaturated α-Ketoesters Catalyzed by an Axially Chiral Guanidine Base
作者:Masahiro Terada、Hiroyuki Nii
DOI:10.1002/chem.201003015
日期:2011.2.7
cycloaddition reaction of azlactones with β,γ‐unsaturated α‐ketoesters was demonstrated by taking advantage of the multiple reactive sites on the azlactone with the use of an axially chiral guanidine‐base catalyst. The most likely reaction pathway involves three consecutive steps to provide a facile access to α‐amino δ‐lactones with a sugar framework in a highly stereoselective manner (see scheme).
Asymmetric organocatalytic sulfenylation for the construction of a diheteroatom-bearing tetrasubstituted carbon centre
作者:Qingfa Tan、Qianping Chen、Zitong Zhu、Xiaohua Liu
DOI:10.1039/d2cc03443c
日期:——
construct diheteroatom-bearing carbon centres was achieved by employing chiral guanidine organocatalysts. This protocol provided a facileroute towards the synthesis of α-fluoro-α-sulfenyl-β-ketoamides, azlactone adducts and α-sulfur-substituted amino acid derivatives in high yields with good to excellent enantioselectivities. A possible working mode was proposed to elucidate the chiral control of