Organocatalytic Access to Enantioenriched Dihydropyran Phosphonates via an Inverse-Electron-Demand Hetero-Diels–Alder Reaction
作者:Christian F. Weise、Vibeke H. Lauridsen、Raoní S. Rambo、Eva H. Iversen、Marie-Luise Olsen、Karl Anker Jørgensen
DOI:10.1021/jo500347a
日期:2014.4.18
hetero-Diels–Alder reaction of the remote olefin functionality in dienamines has been developed by the simultaneous activation of α,β-unsaturated aldehydes and acyl phosphonates. The dual activation is based on an organocatalyst that activates both the α,β-unsaturated aldehyde, through dienamine formation, and the acyl phosphonate by hydrogen-bonding. The enantioselective reaction results in the formation
Intramolecular Sulfur Transfer in <i>N</i><i>-</i>Enoyl Oxazolidine-2-thiones Promoted by Brønsted Acids. Practical Asymmetric Synthesis of β-Mercapto Carboxylic Acids and Mechanistic Insights
作者:Claudio Palomo、Mikel Oiarbide、Rosa López、Pedro B. González、Enrique Gómez-Bengoa、José M. Saá、Anthony Linden
DOI:10.1021/ja0654027
日期:2006.11.1
usually above 95:5. The relative efficiency of a range of acids (trifluoroacetic, difluoroacetic, acetic, triflic) is assessed showing TFA and TfOH as the most efficient and acetic acid as a totally inefficient reaction promoter. The newprocedure complements the Lewis acid promoted reaction previously described by our group in two aspects: First, stereodivergent results are obtained for the Lewis acid
Enantioselective 1,3-Dipolar Cycloadditions of Diazoacetates with Electron-Deficient Olefins
作者:Mukund P. Sibi、Levi M. Stanley、Takahiro Soeta
DOI:10.1021/ol070364x
日期:2007.4.1
[reaction: see text] A general strategy for highly enantioselective 1,3-dipolarcycloaddition of diazoesters to beta-substituted, alpha-substituted, and alpha,beta-disubstituted alpha,beta-unsaturated pyrazolidinone imides is described. Cycloadditions utilizing less reactive alpha,beta-disubstituted dipolarophiles require elevated reaction temperatures, but still provide the corresponding pyrazolines
Diastereoselective Cobalt-Catalyzed Alkylative Aldol Cyclizations Using Trialkylaluminum Reagents
作者:Mairi E. Rudkin、Pekka M. Joensuu、William S. MacLachlan、Hon Wai Lam
DOI:10.1021/ol800883b
日期:2008.7.17
Co(acac)2.2H2O serves as an effective precatalyst for alkylative aldol cyclizations of alpha,beta-unsaturated amides with ketones using trialkylaluminum reagents. These reactions provide beta-hydroxylactams containing three contiguous stereocenters with high levels of diastereoselection.
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。