A catalytic asymmetric version of the exoselective [C+NC+CC] reaction is reported. This multicomponent reaction utilizes a readily prepared achiral glycyl sultam as the "NC" component and commercially available catalyst components. The method can be applied to a variety of aldehydes ("C" component) and activated alkenes ("CC" component) to provide substituted pyrrolidines in good yields and high enantioselectivities. Of particular note is the ability to employ labile enolizable aldehydes (e.g., acetaldehyde and propionaldehyde) in this reaction.
for asymmetric [3+2] cycloaddition reactions. A silver complex prepared from silver bis(trimethylsilyl)amide (AgHMDS) and (R)‐DTBM‐SEGPHOS worked well in asymmetric [3+2] cycloaddition reactions of α‐aminoester Schiff bases with several olefins to afford the corresponding pyrrolidine derivatives in high yields with remarkable exo‐ and enantioselectivities. Furthermore, α‐aminophosphonate Schiff bases
Metal Amides as the Simplest Acid/Base Catalysts for Stereoselective Carbon-Carbon Bond-Forming Reactions
作者:Yasuhiro Yamashita、Shū Kobayashi
DOI:10.1002/chem.201300908
日期:2013.7.15
paper, new possibilities for metalamides are described. Although typical metalamides are recognized as strong stoichiometric bases for deprotonation of inert or less acidic hydrogen atoms, transition‐metalamides, namely silver and copper amides, show interesting abilities as one of the simplestacid/basecatalysts in stereoselectivecarbon–carbon bond‐forming reactions.
Highly Enantioselective Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Ylide Catalyzed by a Copper(I)/ClickFerrophos Complex
作者:Shin-ichi Fukuzawa、Hiroshi Oki
DOI:10.1021/ol8003996
日期:2008.5.1
A copper(I)/ClickFerrophos complexcatalyzed the asymmetric 1,3-dipolar cycloaddition reaction of methyl N-benzylideneglycinate (the source of azomethine ylides) with vinyl sulfone to give the exo-2,4,5-trisubstituted pyrrolidine in good yield with high enantioselectivity (99% ee). The complex also effectively catalyzed reactions of other dipolarophiles such as acrylates, maleate, and maleimides to
Silver lining: Highly exo‐selective asymmetric [3+2] cycloaddition of α‐amino ester Schiff bases with activated olefins proceeds in the presence of AgHMDS/1. The α‐amino ester Schiff bases including those derived from aliphatic imines successfully reacted to afford the corresponding pyrrolidine derivatives in high yield with high exo‐ and enantioselectivities. EWG=electron‐withdrawing group, HMDS=
Cu-catalyzed asymmetric [3+2] cycloaddition of α-iminoamides with activated olefins
作者:María González-Esguevillas、Javier Adrio、Juan C. Carretero
DOI:10.1039/c2cc17149j
日期:——
A variety of 2-amido pyrrolidines, including Weinreb-type amides, have been prepared with very high exo diastereoselectivity and enantioselectivitiy in the reaction of alpha-iminoamides with activated alkenes catalyzed by Cu(I)-Segphos ligands.