α-Chiral Acetylenes Having an All-Carbon Quaternary Center: Phase Transfer Catalyzed Enantioselective α Alkylation of α-Alkyl-α-alkynyl Esters
作者:Takuya Hashimoto、Kazuki Sakata、Keiji Maruoka
DOI:10.1002/anie.200901977
日期:2009.6.22
Going through the phases: The title reaction was found to proceed by an initial base‐mediated isomerization to allenyl esters and subsequent phasetransfercatalyzedalkylation at the α position of the ester (see scheme).
Organocatalytic Enantioselective Synthesis of 2,3-Allenoates by Intermolecular Addition of Nitroalkanes to Activated Enynes
作者:Hui Qian、Xiuzhao Yu、Junliang Zhang、Jianwei Sun
DOI:10.1021/ja409080v
日期:2013.12.4
The first efficient intermolecular addition of nitroalkanes to activated enynes for asymmetric synthesis of 2,3-allenoates is described. It is a new addition to the limited available strategies for catalytic asymmetric synthesis of allenoates. Enabled by a new bifunctional catalyst, a range of trisubstituted allenoates can be obtained in excellent chemical and optical purity. These allenoate products
palladium‐catalyzed decarboxylative coupling of acyclic β,γ‐alkynoic acids with various aryl iodides to chiral tetrasubstituted allenes is described. The coupling reaction comprises a decarboxylative γ‐palladation of α,α‐disubstituted carboxylic acids to provide the tetrasubstituted allenes with complete point‐to‐axial chirality transfer in excellent yields.