Enantioselective Synthesis of Tertiary α,α-Diaryl Carbonyl Compounds Using Chiral <i>N,N′</i>-Dioxides under Umpolung Conditions
作者:Tae-Woong Um、Girim Lee、Seunghoon Shin
DOI:10.1021/acs.orglett.0c00333
日期:2020.3.6
addition of the chiral N,N'-dioxide into ynamides generated enolonium ions in situ which underwent enantioselective alkylation by indoles, pyrroles, and phenols, without racemization of the formed tertiary center. This external oxidant approach allows for the use of unmodified nucleophiles and does not leave trace groups from the oxidant, which significantly increases the synthetic efficiency and the
Aminooxygenation of Ynamides with <i>N-</i>Hydroxybenzotriazoles: Synthesis of α-Benzotriazolyl Carbonyl Compounds
作者:Jangbin Im、Sang Ik Shin、Cheon-Gyu Cho、Seunghoon Shin
DOI:10.1021/acs.joc.0c00174
日期:2020.6.5
any catalyst but could be efficientlycatalyzed by Zn(OTf)2. Crossover experiments confirmed that the rearrangement is an intramolecular process, most likely via a concerted mechanism. However, heating the mixture above 110 °C resulted in isomerization of N2 into N1 product, via heterolytic C–N bond dissociation. This tandem addition–rearrangement sequence provides an efficient and atom-economical synthetic
Dual role of DMSO in the intermolecular oxygenative bifunctionalization of ynamides
作者:Kexin Gao、Shenyue Xie、Xialei Chen、Guoying Qian、Zhouting Rong
DOI:10.1016/j.tetlet.2024.154943
日期:2024.3
A simple HNTf2/DMSO system has been developed for the intermolecular oxgenative bifunctionalization of ynamides to produce various α-functionalized amides, where DMSO functions both as the oxygen donor and the solvent. Scope study shows that electron-rich ynamides and nucleophiles such as alcohols, thiols and electron-rich arenes are suitable reaction partners in this transformation.
β-Oxidation of Ynamides into <i>N</i>,<i>O-</i>Acetals by <i>m</i>CPBA: Application in Enantioselective Intermolecular Transacetalization
作者:Nguyen H. Nguyen、Quynh H. Nguyen、Soumen Biswas、Dilip V. Patil、Seunghoon Shin
DOI:10.1021/acs.orglett.9b03411
日期:2019.11.15
Oxidation of ynamides by mCPBA led to beta-oxygenation and resulted in formation of carbonyl compounds with alpha-N,O-acetal functionality. These N,O-acetals are formed in high yields and can be stored indefinitely at room temperature. Yet, they can be activated by a chiral Bronsted acid and underwent an enantioselective transacetalization into a alpha-N,O-acetal. Subsequent diastereoselective transformations occurred with exceptional selectivity according to Felkin-Anh model.
Copper-Catalyzed Aerobic Oxidative Amidation of Terminal Alkynes: Efficient Synthesis of Ynamides
作者:Tetsuya Hamada、Xuan Ye、Shannon S. Stahl
DOI:10.1021/ja077406x
日期:2008.1.1
A copper-catalyzed method for the preparation of ynamides has been identified that proceeds via aerobicoxidative coupling of terminal alkynes with various nitrogen nucleophiles, including cyclic carbamates, amides and ureas, and N-alkyl-arylsulfonamides and indoles.