The Pd-catalyzed cross-coupling of allylic carbonates and allyIB(pin) is described. The regioselectivity of this reaction is sensitive to the bite angle of the ligand, with small-bite-angle ligands favoring the branched substitution product. This mode of regioselection is consistent with a reaction that operates by a 3,3' reductive elimination reaction. In the presence of appropriate chiral ligands, this reaction is rendered enantioselective and applies to both aromatic and aliphatic allylic carbonates.
Gold-catalyzed Prins-type cyclizations are interesting strategies for synthesizing complex molecules with excellent diastereoselectivity. We developed a novel and efficient system for such processes (13 examples, ≤89% yield) and reported the first enantioselective version of a gold-catalyzed Prins-type cyclizationusing a new chiral TADDOL-based Au(I) phosphonite complex. After crystallization, highly
Scope and Mechanism of the Pt-Catalyzed Enantioselective Diboration of Monosubstituted Alkenes
作者:John R. Coombs、Fredrik Haeffner、Laura T. Kliman、James P. Morken
DOI:10.1021/ja4041016
日期:2013.7.31
The Pt-catalyzed enantioselective diboration of terminal alkenes can be accomplished in an enantioselective fashion in the presence of chiral phosphonite ligands. Optimal procedures and the substrate scope of this transformation are fully investigated. Reaction progress kinetic analysis and kinetic isotope effects suggest that the stereodefining step in the catalytic cycle is olefin migratory insertion
Asymmetric Ni-Catalyzed Conjugate Allylation of Activated Enones
作者:Joshua D. Sieber、James P. Morken
DOI:10.1021/ja710922h
日期:2008.4.1
The nickel-catalyzedenantioselective addition of allylboronic acid pinacol ester, allylB(pin), is described. This reaction is highly effective with dialkylidene ketones and favors the allylation of the benzylidene site in nonsymmetric substrates. The reaction appears to proceed by conversion of the dialkylidene ketone substrate to an unsaturated pi-allyl complex (I), followed by reductive elimination