Amide phosphonium salt catalyzed enantioselective Mannich addition of isoxazole-based nucleophiles to β,γ-alkynyl-α-ketimino esters
Congzheng Gu, Guangzheng Tian, Qingyu Yin, Fan Wu, Zhiming Li, Xiaoyu Wu
Abstract
-Cbz-protected ketimino esters with various aryl substituents attached to the alkyne unit were reacted with a series of isoxazoles with different substitution patterns. Chiral tertiary propargylic amine products were obtained with moderate to good yields and enantioselectivities. TIPS- and cyclopropyl-substituted alkynyl ketimines were also examined in the current system and the desired products were obtained with moderate yields and enantioselectivities. The potential scalability and utility of the current protocol were demonstrated by carrying out a relatively larger scale reaction followed by further transformations.
Topics & Concepts
ChemistryEnantioselective synthesisIsoxazolePhosphonium saltAmideAlkynePhosphoniumCatalysisNucleophileAmine gas treatingOrganic chemistrySalt (chemistry)ArylCombinatorial chemistryMedicinal chemistryAlkylAsymmetric Synthesis and CatalysisChemical Synthesis and AnalysisSynthesis and Catalytic Reactions