[2 + 2 + 1] Heteroannulation of Alkenes with Enynyl Benziodoxolones and Silver Nitrite Involving C≡C bond Oxidative Cleavage: Entry to 3-Aryl-Δ<sup>2</sup>-isoxazolines
作者:Cheng-Yong Wang、Fan Teng、Yang Li、Jin-Heng Li
DOI:10.1021/acs.orglett.0c01285
日期:2020.6.5
A copper-catalyzed [2 + 2 + 1] heteroannulation of alkenes with enynyl benziodoxolones and AgNO2 involving oxidative cleavage of the C≡C bond promoted by cooperative Zn(OTf)2, KOAc, and 4 Å MS for producing 3-aryl Δ2-isoxazolines is reported. Mechanistic studies indicate that AgNO2 serves as the N/O two-atom unit source, enabling the formation of three bonds through NO2 addition across the C≡C bond
9,10-Dicyanoanthracene-sensitized photoreaction of electron-rich 1,2-diarylcyclopropanes with NO in acetonitrile afforded 3,5-diaryl-2-isoxazolines in good yields. The cyclopropanes bearing different aryl-substituents gave a mixture of two isomeric 2-isoxazolines. Mechanistic features of this reaction are described.
of 1,2-diarylcyclopropanes with NOBF4 in CH3CN gave 3,5-diaryl-2-isoxazolines in good yields. For unsymmetrically substituted cyclopropanes, the mixtures of two isomeric isoxazolines were obtained. The mechanism and regioselectivity in this NO insertion into the cyclopropane ring are described.
1,2-二芳基环丙烷与 NOBF4 在 CH3CN 中的反应以良好的收率得到 3,5-二芳基-2-异恶唑啉。对于不对称取代的环丙烷,获得了两种异构异恶唑啉的混合物。描述了这种 NO 插入环丙烷环的机制和区域选择性。
Insertion of nitrogen oxide and nitrosonium ion into the cyclopropane ring: a new route to 2-isoxazolines and its mechanistic studies
The 9,10-dicyanoanthracene (DCA)-sensitized photoreaction of 1,2-diarylcyclopropanes 1a-d in nitrogen oxide (NO)-saturated CH3CN afforded 3,5-diaryl-2-isoxazolines 2a-d in excellent yields. The reaction of 1a-d with NOBF4 or with a mixture of NO and O2 in CH3CN also afforded 2a-d or 2a-b. These reactions proceed via the attack of NO on the radical cation of 1, which is formed by electron transfer from 1 to 1DCA* or NO+. The reaction of 1-alkyl-2-arylcyclopropanes with NOBF4 afforded mixtures of 3-alkyl-5-aryl-2-isoxazolines and 4-alkyl-5-aryl-2-isoxazolines via the direct attack of NO+ on the cyclopropane rings. The reaction of 1,1,2,2-tetraphenylcyclopropane with NOBF4 afforded 2,3,5,5-tetraphenyl-2-isoxazolinium tetrafluoroborate via the migration of the phenyl group to nitrogen.
Mochalov; Kuz'min; Fedotov, Russian Journal of Organic Chemistry, 1998, vol. 34, # 9, p. 1322 - 1330