在此,我们提出了一种以 H 2 O 作为绿色氧源电化学诱导芳基环丙烷 1,3-氧代羟基化的方法。这种转化为在无氧化剂和无金属条件下制备高度功能化的β-羟基酮提供了一条区域选择性途径。值得注意的是,该电化学方法具有操作简单、区域选择性好、官能团耐受性高、产物易于衍生化等特点。机理研究提供了确凿的证据,证明 1,3-二醇是该反应中的关键中间体,导致观察到的区域选择性。
Reductive Cyclopropanations Catalyzed by Dinuclear Nickel Complexes
作者:You-Yun Zhou、Christopher Uyeda
DOI:10.1002/anie.201511271
日期:2016.2.24
Dinuclear Ni complexes supported by naphthyridine‐diimine (NDI) ligands catalyze the reductive cyclopropanation of alkenes with CH2Cl2 as the methylene source. The use of mild terminal reductants (Zn or Et2Zn) confers significant functional‐group tolerance, and the catalyst accommodates structurally and electronically diverse alkenes. Mononickel catalysts bearing related N chelates afford comparatively
A Stereoconvergent Cyclopropanation Reaction of Styrenes
作者:Ana M. del Hoyo、Ana G. Herraiz、Marcos G. Suero
DOI:10.1002/anie.201610924
日期:2017.2
The first stereoconvergent cyclopropanation reaction by means of photoredox catalysis using diiodomethane as the methylene source is described. This transformation exhibits broad functional group tolerance and it is characterized by an excellent stereocontrol en route to trans‐cyclopropanes regardless of whether E‐ or Z‐styrene substrates were utilized.
Electrochemical ring-opening 1,3-dihydroxylation of arylcyclopropanes with H<sub>2</sub>O
作者:Jianhua Cai、Yuxi Wen、Wei Sheng、Xuejin Huang、Ye Zheng、Chunlan Song、Jiakun Li
DOI:10.1039/d3gc02283h
日期:——
dihydroxylation of alkenes is one of the most powerful synthetic tools for delivering two hydroxyl groups at vicinal positions. The direct formation of 1,3-diols remains a formidable challenge, yet dihydroxyl groups are broadly present in bioactive compounds, and are currently only available synthetically via multiple steps. The oxidative ring-opening of arylcyclopropanes has been demonstrated to access various
传统的烯烃二羟基化是在邻位提供两个羟基的最强大的合成工具之一。直接形成 1,3-二醇仍然是一个艰巨的挑战,但二羟基广泛存在于生物活性化合物中,目前只能通过多个步骤合成。芳基环丙烷的氧化开环已被证明可以得到各种 1,3-双官能化化学物质,但由于 1,3-二醇本身很容易被进一步氧化,所以尚未直接合成 1,3-二醇。在此,我们报告了一种简便有效的 1,3-二醇策略,涉及用 H 2控制芳基环丙烷的电化学 C-C 键断裂O作为最终的绿色羟基源。此外,该方案以其高原子经济性、广泛的底物范围和优异的官能团耐受性而脱颖而出,因此适合复杂天然产物和药物衍生物的合成。
Highly Diastereoselective Hydrostannylation of Allyl and Homoallyl Alcohols with Dibutyl(trifluoromethanesulfoxy)stannane
作者:Katsukiyo Miura、Di Wang、Akira Hosomi
DOI:10.1021/ja052245n
日期:2005.7.1
Dibutyl(trifluoromethanesulfoxy)stannane (Bu2Sn(OTf)H, 1a) was found to be very valuable for highly diastereoselective homolytic hydrostannylation of allyl and homoallyl alcohols. alpha,beta-Disubstituted allyl alcohols and alpha,gamma-disubstituted homoallyl alcohols were converted into gamma- and delta-stannylated alcohols with high 1,2-syn and 1,3-syn diastereoselectivity, respectively. The origin of the stereochemical outcomes can be rationalized by conformational fixation of the intermediary beta-stannylalkyl radical by coordination of the hydroxy group to the Lewis acidic tin center.
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.