Iodine/Visible Light Photocatalysis for Activation of Alkynes for Electrophilic Cyclization Reactions
作者:Yuliang Liu、Bin Wang、Xiaofeng Qiao、Chen-Ho Tung、Yifeng Wang
DOI:10.1021/acscatal.7b00799
日期:2017.6.2
Photocatalytic organic synthesis needs photocatalysts to initiate the reactions and to control the reaction paths. Available photocatalytic systems rely on electron transfer or energy transfer between the photoexcited catalysts and the substrates. We explore a concept based on the photopromoted catalyst coupling to the substrate and the phototriggered catalyst regeneration by elimination from the catalytic
Preparation of oxazolines and oxazoles<i>via</i>a PhI(OAc)<sub>2</sub>-promoted cyclization of<i>N</i>-propargylamides
作者:Wei Yi、Qing-Yun Liu、Xing-Xiao Fang、Sheng-Chun Lou、Gong-Qing Liu
DOI:10.1039/c8ob01474d
日期:——
A metal-free cyclization of N-propargylamides for the synthesis of various oxazolines and oxazoles via a 5-exo-dig process is presented. Using (diacetoxyiodo)benzene (PIDA) as a reaction promoter and lithium iodide (LiI) as an iodine source, intramolecular iodooxygenation of N-propargylamides proceeded readily, leading to the corresponding (E)-5-iodomethylene-2-oxazolines in good to excellent isolated
Electrochemical Organoselenium Catalysis for the Selective Activation of Alkynes: Easy Access to Carbonyl-pyrroles/oxazoles from <i>N</i>-Propargyl Enamines/Amides
作者:Mrinmay Baidya、Jhilik Dutta、Suman De Sarkar
DOI:10.1021/acs.orglett.3c01355
日期:2023.5.26
Intramolecular electro-oxidative addition of enamines or amides to nonactivated alkynes was attained to access carbonyl-pyrroles or -oxazoles from N-propargyl derivatives. Organoselenium was employed as the electrocatalyst, which played a crucial role as a π-Lewis acid and selectively activated the alkyne for the successful nucleophilic addition. The synthetic strategy permits a wide range of substrate
Intramolecular Pd(II)-Catalyzed Cyclization of Propargylamides: Straightforward Synthesis of 5-Oxazolecarbaldehydes
作者:Egle M. Beccalli、Elena Borsini、Gianluigi Broggini、Giovanni Palmisano、Silvia Sottocornola
DOI:10.1021/jo800621n
日期:2008.6.1
Direct synthesis of 2-substituted 5-oxazolecarbaldehydes was performed by intramolecular reaction of propargylamides through treatment with a catalytic amount of Pd(II) salts in the presence of a stoichiometric amount of reoxidant agent. The heterocyclization process was well-tolerated by a wide range of aryl, heteroaryl, and alkyl propargylamides. This protocol constitutes a valuable synthetic pathway to 5-oxazolecarbaldehydes, alternative to the formylation on oxazole rings, often unsatisfactory in term of regioselectivity and yields.
Synthesis of novel 1,3-oxazole derivatives with insect growth-inhibiting activities
Abstract Straightforward and direct synthesis of 2-substituted-5-oxazolecarbaldehydes was achieved by treating propargylamides with mercury(II) perchlorate as catalyst and ammonium cerium(IV) nitrate as oxidant agent through intramolecular cyclization. These structurally interesting outcomes benefit to synthesize 2,5-disubstituted-1,3-oxazoles with armyworm growth regulating activities.