The intermolecular diastereoselective and enantioselective synthesis of pyrrolo[1,2-a]indoles is developed through a [3+2] cycloaddition between silyl-indole derivatives and α,β-unsaturated N-acyl oxazolidinones by merging photocatalysis and Lewis acid catalysis.
吡咯并[1,2- a ]吲哚的分子间非对映选择性和对映选择性合成是通过甲硅烷基吲哚衍生物与α,β-不饱和N-酰基恶唑烷酮通过光催化和路易斯酸催化的[3 + 2]环加成反应而开发的。
Chiral Lewis Acid Catalysis in Nitrile Oxide Cycloadditions
作者:Mukund P. Sibi、Kennosuke Itoh、Craig P. Jasperse
DOI:10.1021/ja0318636
日期:2004.5.1
examples of highly regio- and enantioselective nitrileoxidecycloadditions to unsaturated alkenes using substoichiometric amounts of a chiral Lewis acid. Pyrazolidinones proved to be effective achiral templates in the cycloadditions providing C-adducts typically in >30:1 selectivity and 80-99% ee. To avoid potential problems involving coordination of the Lewis acid by amine bases, we have devised a novel
Enantioselective Conjugate Additions of α-Amino Radicals via Cooperative Photoredox and Lewis Acid Catalysis
作者:Laura Ruiz Espelt、Iain S. McPherson、Eric M. Wiensch、Tehshik P. Yoon
DOI:10.1021/ja512746q
日期:2015.2.25
We report the highly enantioselective addition of photogenerated α-amino radicals to Michael acceptors. This method features a dual-catalyst protocol that combines transition metal photoredox catalysis with chiral Lewisacidcatalysis. The combination of these two powerful modes of catalysis provides an effective, general strategy to generate and control the reactivity of photogenerated reactive intermediates
We have developed a novel method for accessing exo adducts with high enantioselectivity in nitrone cycloadditions to enoates. Pyrazolidinones proved to be effective achiral templates in the cycloadditions, providing exo adducts typically in >15:1 selectivity and 90-98% ee. The use of Lewis acids that form square planar complexes, such as copper triflate, was important for obtaining high exo selectivity.
Enantioselective Conjugate Addition of Hydroxylamines to Pyrazolidinone Acrylamides
作者:Mukund P. Sibi、Mei Liu
DOI:10.1021/ol016807t
日期:2001.12.1
[GRAPHICS]Chiral relay templates provide amplification of selectivity in conjugate addition reactions. Reversal of stereochemistry of the product isoxazolidinones has also been demonstrated by a simple change of the Lewis acid.