Direct Asymmetric α-Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts
作者:Gaoxi Jiang、Benjamin List
DOI:10.1002/anie.201103263
日期:2011.9.26
catalysis: The title reaction between α‐branched aldehydes and allylic alcohols, which generates all‐carbon quaternary stereogenic centers, constitutes the first asymmetric Tsuji–Trost‐type α‐allylation of carbonyl compounds with allylic alcohol (see scheme). This reaction is catalyzed by three different species, [Pd(PPh3)4], the chiralBrønstedacid TRIP, and benzhydryl amine.
Enantioselective Construction of Quaternary Stereogenic Centers from Tertiary Boronic Esters: Methodology and Applications
作者:Ravindra P. Sonawane、Vishal Jheengut、Constantinos Rabalakos、Robin Larouche-Gauthier、Helen K. Scott、Varinder K. Aggarwal
DOI:10.1002/anie.201008067
日期:2011.4.11
that bear versatile functional groups with quaternary stereogenic centers have been prepared with very high enantioselectivity from tertiaryboronicesters (see scheme; Cb=N,N‐diisopropylcarbamoyl, pin=pinacolato). The preparation of allylboronic esters bearing contiguous quaternary and tertiary stereogenic centers, and applications to natural product synthesis are also reported.
Asymmetric synthesis of enantioenriched α-allyl esters through Pd(BINAPHANE)-catalysed allylation of disubstituted ketenes
作者:Ahmad A. Ibrahim、Stephen C. J. O’Reilly、Margot Bottarel、Nessan J. Kerrigan
DOI:10.1039/d4cc00057a
日期:2024.3.19
Pd2dba3·CHCl3 (2.5 mol%)-BINAPHANE (5 mol%) was used to promote the first catalytic enantioselective allylation of disubstituted ketenes to give α-allyl esters. The ester products were formed in good to excellent yields (61–93% yield for 13 examples, 16 examples in all), with moderate to good enantioselectivity (68–80% ee for 7 examples).
Chemo- and Enantioselective Pd/B Hybrid Catalysis for the Construction of Acyclic Quaternary Carbons: Migratory Allylation of <i>O</i>-Allyl Esters to α-<i>C</i>-Allyl Carboxylic Acids
We describe herein the asymmetric synthesis of α-allyl carboxylic acids containing an α-quaternarystereocenter by a chiral hybrid catalyst system comprising palladium and boron complexes. The reaction proceeded through palladium-catalyzed ionization of α,α-disubstituted O-allyl esters for the generation of chiral π-allyl palladium complex as an electrophile, boron-catalyzed enolization of the carboxylate