Palladium(II)-Catalyzed SN2‘ Reactions of α-Allenic Acetates. Stereoconvergent Synthesis of (Z,E)-2-Bromo-1,3-dienes
摘要:
The reaction of acetylated a-allenic alcohols with LiBr in the presence of 1.5 mol % of Pd(OAc)(2) provides easy access to substituted (Z,E)-2-bromo-1,3-dienes in good yields with excellent diastereoselectivity. Both secondary and tertiary acetates as well as terminal and nonterminal allenes were studied to investigate the scope and the limitations of the reaction. A mechanism is proposed to clarify how a diastereomeric mixture of the starting compound is transformed into a single diastereomer of the product.
Catalytic Asymmetric Allenylation of Malonates with the Generation of Central Chirality
作者:Qiankun Li、Chunling Fu、Shengming Ma
DOI:10.1002/anie.201204346
日期:2012.11.19
Water plays an important role in a palladium‐catalyzed allenylation of diethyl malonate with 2,3‐allenyl acetates to yield centrallychiral allenyl malonates bearing synthetically useful functional groups (see scheme). The products were formed with 92–96 % ee in the presence of a bulky, electron‐rich biphenyl ligand at room temperature.
Catalytic Enantioselective Simultaneous Control of Axial Chirality and Central Chirality in Allenes
作者:Jianxin Dai、Xinyu Duan、Jing Zhou、Chunling Fu、Shengming Ma
DOI:10.1002/cjoc.201800090
日期:2018.5
to report a protocol for preparation of chiral allenes with both central and axial chiralities via a catalyticasymmetricallenylation of different biologically or synthetically useful fluorinated or non‐fluorinated nucleophiles with readily available racemic allenes by using a single chiral ligand. An echoing between the centralchirality and axial chirality for the enantioselectivity was observed