Enantioselective Thiourea-Catalyzed Additions to Oxocarbenium Ions
作者:Sarah E. Reisman、Abigail G. Doyle、Eric N. Jacobsen
DOI:10.1021/ja801514m
日期:2008.6.1
Asymmetric, catalytic reactions of oxocarbeniumions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbeniumion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest enantioselectivities
Hydrogen‐Bonding‐Promoted Cascade Rearrangement Involving the Enlargement of Two Rings: Efficient Access to Polycyclic Quinoline Derivatives
作者:Wen‐Bin Cao、Shijun Li、Meng‐Meng Xu、Haiyan Li、Xiao‐Ping Xu、Yu Lan、Shun‐Jun Ji
DOI:10.1002/anie.202008110
日期:2020.11.23
An efficient cascade reaction of tryptamine‐derived isocyanides with C,N‐cyclic azomethine imines is described. The polycyclic pyrrolo[2,3‐c]quinoline derivatives, which benefited from rearrangement process driven by hydrogen bonding, could be directly assembled in moderate to good yields (40–87 %) under metal‐free and mild conditions. This transformation involved four new heterocyclic rings formations
A phosphane‐catalyzed [3+3] annulation of azomethineimines with ynones has been developed. Under mild reaction conditions, the reaction proceeds smoothly to afford tricyclic dinitrogen‐fused heterocyclic compounds in moderate to excellent yields with moderate to excellent stereoselectivies. Using a chiral phosphine as the catalyst, the reaction could work to give the cycloadduct in moderate yield
Enantioselective Copper-Catalyzed Alkynylation of Benzopyranyl Oxocarbenium Ions
作者:Harathi D. Srinivas、Prantik Maity、Glenn P. A. Yap、Mary P. Watson
DOI:10.1021/acs.joc.5b00364
日期:2015.4.17
We have developed highly enantioselective, copper-catalyzedalkynylations of benzopyranyl acetals. By using a copper(I) catalyst equipped with a chiral bis(oxazoline) ligand, high yields and enantioselectivities are achieved in the alkynylation of widely available, racemic isochroman and chromene acetals to deliver α-chiral oxygen heterocycles. This method demonstrates that chiral organometallic nucleophiles
A yet-unexploited class of azomethine imines, C,N-cyclic azomethine imines, could be successfully employed in highly enantioselective1,3-dipolarcycloaddition with enals catalyzed by titanium-BINOLate to give pharmaceutically attractive tetrahydroisoquinoline and piperidine motifs.