Unusual Reactivity of 4-Vinyl Isoxazoles in the Copper-Mediated Synthesis of Pyridines, Employing DMSO as a One-Carbon Surrogate
作者:Pravin Kumar、Manmohan Kapur
DOI:10.1021/acs.orglett.0c01935
日期:2020.8.7
An efficient protocol for the synthesis of nicotinate derivatives and tetrasubstituted pyridines through a copper-mediated cleavage of isoxazoles has been developed. The highlight of the work is the observation of an unusualreactivity of 4-vinyl isoxazoles under the reaction conditions. DMSO serves as a one-carbon surrogate generating an active methylene group during the reaction to form two C–C bonds
A general access to isoxazoles with outstanding functional group compatibility from the readily available ynones using trimethylsilyl azide as an amino surrogate under exceptionally simple conditions is described.
Copper-catalyzed aerobic oxidative C–O bond formation for the synthesis of 3,5-disubstituted isoxazoles from enone oximes
作者:Yadong Sun、Ablimit Abdukader、Haiyan Zhang、Wanle Yang、Chenjiang Liu
DOI:10.1039/c7ra11436b
日期:——
oxidative coupling reaction of enone oximes using a catalytic quantity of Cu(OAc)2. This method features an inexpensive metal catalyst, molecular oxygen as a green oxidant, good functional group tolerance and readily available starting materials. This attractive method for the synthesis of isoxazole derivatives is of great significance due to the product's versatile reactivity for further transformations.
Isoxazole as a nitrile synthon: <i>en routes</i> to the <i>ortho</i>-alkenylated isoxazole and benzonitrile with allyl sulfone catalyzed by Ru(<scp>ii</scp>)
作者:Pritishree Panigrahi、Subhendu Ghosh、Tamanna Khandelia、Raju Mandal、Bhisma K. Patel
DOI:10.1039/d3cc02996d
日期:——
A Ru(II) catalyzedregioselective Heck-type C–H olefination of isoxazole with unactivated allyl phenyl sulfone is revealed. The solvent DCM offers dual sp2–sp2 C–Hactivation via an N-directed strategy, leading to ortho-olefinated isoxazoles with exclusive E-selectivity. On the other hand, in DCE solvent, isoxazole serves as the nitrile synthon and leads to o-olefinated benzonitrile. At a higher temperature