Palladium-Catalyzed Asymmetric Allylic Alkylation of Ketone Enolates
作者:Barry M. Trost、Gretchen M. Schroeder
DOI:10.1002/chem.200400666
日期:2005.1
Palladium-catalyzed asymmetric allylic alkylation of nonstabilized ketone enolates to generate quaternary centers has been achieved in excellent yield and enantioselectivity. Optimized conditions consist of performing the reaction in the presence of two equivalents of LDA as base, one equivalent of trimethytin chloride as a Lewis acid, 1,2-dimethoxyethane as the solvent, and a catalytic amount of a
Novel Chiral Diamino-Oligothiophenes as Valuable Ligands in Pd-Catalyzed Allylic Alkylations. On the “Primary” Role of “Secondary” Interactions in Asymmetric Catalysis
A new class of chiral C2-symmetrical diamino-oligothiophenes is described to be effective in catalyzing Pd-mediated asymmetricallylicalkylations in a highly enantioselective manner. The combination of experimental as well as crystallographic evidence revealed the key role played by sulfur-based heteroaromatic rings in the stereodiscriminating step of the procedure. In particular, unprecedented non-covalent
Enantiomerically pure diamino-bis(tert-thiophene) 1b proved to be a valuable and flexible chiral ligand for Pd- and Zn-catalyzed transformations, allowing for high levels of stereocontrol in asymmetric allylic alkylation (ee up to 99%) and hydrosilylations of prochiral carbonyls (ee up to 97%).
Palladium-Catalyzed Enantioselective Allylic Substitution in the Presence of Monodentate Furanoside Phosphoramidites
作者:Maciej Majdecki、Janusz Jurczak、Tomasz Bauer
DOI:10.1002/cctc.201402933
日期:2015.3
D‐xylose and optically pure 1,1′‐bi‐2‐naphthol (BINOL), was used as ligands for the palladium‐catalyzed allylic alkylation and amination. The matched pair was formed from D‐xylose‐derivatives and (S)‐BINOL. The asymmetricinduction depends strongly on the substituent at the C5 of the carbohydrate backbone; both bulky 5‐O‐pivaloyl and 5‐deoxy derivatives gave excellent results, whereas ligands with trityl
Palladium-Catalyzed Allylic Alkylation of Doubly Deprotonated Carboxylic Acids
作者:Manfred Braun、Panos Meletis、Robin Visse
DOI:10.1002/adsc.201100372
日期:2011.12
Doublydeprotonatedcarboxylicacids undergo smooth palladium-catalyzed carbon alkylations with the allylic substrates methyl allyl carbonate and (E)-methyl (pent-3-en-2-yl) carbonate to give γ,δ-unsaturated carboxylicacids. A diastereoselective and enantioselective protocol leads to (2S,3R)-hexenoic acid in 87% ee.