Evaluation of Catalyst Acidity and Substrate Electronic Effects in a Hydrogen Bond-Catalyzed Enantioselective Reaction
作者:Katrina H. Jensen、Matthew S. Sigman
DOI:10.1021/jo1013806
日期:2010.11.5
A modular catalyst structure was applied to evaluate the effects of catalystacidity in a hydrogen bond-catalyzed hetero Diels−Alder reaction. Linear free energy relationships between catalystacidity and both rate and enantioselectivity were observed, where greater catalystacidity leads to increased activity and enantioselectivity. A relationship between reactant electronic nature and rate was also
The present invention relates to a process for stereoselective cycloaddition reactions which generally comprises a cycloaddition reaction between a pair of substrates, each either chiral or prochiral, that contain reactive &pgr;-systems, in the presence of a non-racemic chiral catalyst, to produce a stereoisomerically enriched product. The present invention also relates to novel asymmetric catalyst complexes comprising a metal and an asymmetric tridentate ligand.
Preparation of Dendritic and Non-Dendritic Styryl-Substituted Salens for Cross-Linking Suspension Copolymerization with Styrene and Multiple Use of the Corresponding Mn and Cr Complexes in Enantioselective Epoxidations and Hetero-Diels–Alder Reactions
作者:Holger Sellner、Jaana K. Karjalainen、Dieter Seebach
than 95% of the Salen incorporated being actually accessible for complexation (by elemental analysis). The polymer-bound Mn and Cr complexes were used as catalysts for epoxidations of six phenyl-substitutedolefins (m-CPBA/NMO; products 22a-f), and for dihydropyranone formation from the Danishefsky diene and aldehydes (PhCHO, C5H11CHO, C6H11CHO, products 23a-c). There are several remarkable features
Chiral Hetero Diels−Alder Products by Enantioselective and Diastereoselective Zirconium Catalysis. Scope, Limitation, Mechanism, and Application to the Concise Synthesis of (+)-Prelactone C and (+)-9-Deoxygoniopypyrone
enantioselectivities in the reaction with 4-methyl Danishefsky's diene. This is the first example of catalyticasymmetric trans-selective hetero Diels-Alderreactions of aldehydes. Furthermore, asymmetric HDA reactions with 4-benzyloxy Danishefsky's dienes were conducted to afford 2,3-cis-pyranone derivatives in high selectivities. Isolation of an intermediate of this asymmetric hetero Diels-Alderreaction indicated
Catalytic, Enantioselective Hetero-Diels-Alder Reaction with Novel, Chiral Bis-Titanium(IV) Catalyst
作者:Satoshi Kii、Takuya Hashimoto、Keiji Maruoka
DOI:10.1055/s-2002-31927
日期:——
Our recently designed chiral bis-titanium(IV) catalyst can be successfully utilized for the catalyticenantioselective hetero-Diels-Alder reaction of aldehyde and Danishefsky's diene. The high asymmetric induction is achievable in the case of sterically less hindered aldehydes.