- Copper-catalyzed radical oxyallylation of olefins for the construction of alkene-containing isoxazolines
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A radical-mediated approach to alkene oxyallylation using allylic oximes is described. The reaction proceeds under copper-catalytic redox-neutral conditions and tolerates various functional groups. This protocol thus enables the synthesis of structurally valuable isoxazolines and the introduction of a versatile olefin motif in a single step.
- He, Xiaoxue,Qian, Lijie,Dai, Yuyu,Yan, Xinhuan,Li, Xiaoqing,Xu, Xiangsheng
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- Copper-Catalyzed Aerobic Cyclization of β,γ-Unsaturated Hydrazones with Concomitant CC Bond Cleavage
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A Cu-catalyzed aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant CC bond cleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an 18O-labeling method, and the identification of the possible byproducts. The advantages of this reaction include operational simplicity, a broad reaction scope, and a mild selective reaction process.
- Fan, Zhenwei,Feng, Jiahao,Hou, Yuchen,Rao, Min,Cheng, Jiajia
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p. 7981 - 7985
(2020/11/02)
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- Palladium-Catalyzed Allylic Alkylation of 2-Aryl-1,3-Dithianes, an Umpolung Synthesis of β,γ-Unsaturated Ketones
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Palladium-catalyzed allylic alkylation of 2-aryl-1,3-dithianes at room temperature is described. A variety of cyclic and acyclic electrophiles successfully coupled with in-situ generated 2-sodio-1,3-dithiane nucleophiles to afford the allylated products in good to excellent yields (25 examples). Deprotection of these products leads to valuable β,γ-unsaturated ketones. Direct synthesis of such β,γ-unsaturated ketones via a one-pot allylation-oxidation protocol is also presented. Investigation into the stereochemistry of the allylation reaction revealed that the 2-sodio-1,3-dithiane nucleophile behaves as a “soft” nucleophile, which underwent external attack on the π-allyl palladium complex to provide retention of stereochemistry (double inversion pathway). Additionally, the utility of this method was demonstrated through a sequential one-pot allylation-Heck cyclization to produce asterogynin derivatives, which are important bioactive compounds in medicinal chemistry. (Figure presented.).
- Trongsiriwat, Nisalak,Li, Minyan,Pascual-Escudero, Ana,Yucel, Baris,Walsh, Patrick J.
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supporting information
p. 502 - 509
(2018/12/11)
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- Iminoxyl Radical-Promoted Oxycyanation and Aminocyanation of Unactivated Alkenes: Synthesis of Cyano-Featured Isoxazolines and Cyclic Nitrones
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A novel and facile approach to vicinal oxycyanation and aminocyanation of internal unactivated alkenes is developed. This method utilizes the dichotomous reactivity of iminoxyl radical derived from the initiation of β,γ- and γ,δ-unsaturated ketoximes to provide the general difunctionalization of internal alkenes using tert-butyl hydroperoxide (TBHP) as the environmentally friendly oxidant, CuCN as the commercially available cyanating reagent, and pentamethyldiethylenetriamine (PMDETA) as the ligand. By using this protocol, a series of useful cyano-featured isoxazolines and cyclic nitrones were efficiently prepared.
- Chen, Fei,Zhu, Fei-Fei,Zhang, Man,Liu, Rui-Hua,Yu, Wei,Han, Bing
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p. 3255 - 3258
(2017/06/23)
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- Green organocatalytic synthesis of isoxazolines via a one-pot oxidation of allyloximes
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A green, sustainable, organocatalytic, and efficient synthesis of isoxazolines from allyloximes was developed. A 2,2,2-trifluoroacetophenone-catalyzed oxidation of allyloximes, utilizing H2O2 as the green oxidant, was taken advantage of in order to introduce a cheap and environmentally friendly protocol for the synthesis of substituted isoxazolines. A variety of substitution patterns, both aromatic and aliphatic moieties, are well tolerated, leading to isoxazolines in moderate to excellent yields.
- Triandafillidi, Ierasia,Kokotos, Christoforos G.
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p. 106 - 109
(2017/11/27)
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- Metal-Free Autoxidative Nitrooxylation of Alkenyl Oximes with Molecular Oxygen
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A metal-free aerobic autoxidative nitrooxylation of alkenyl oximes mediated by tert-butyl nitrite is described. Molecular oxygen is used as the oxidizing reagent, avoiding use of organic trapping reagents such as 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMP
- Zhang, Xiao-Wei,Xiao, Zu-Feng,Zhuang, Yan-Jun,Wang, Mei-Mei,Kang, Yan-Biao
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p. 1942 - 1945
(2016/07/06)
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- Transition-metal-free oxychlorination of alkenyl oximes:: In situ generated radicals with tert -butyl nitrite
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Oxychlorination of alkenyl oximes is harder compared to the analogous oxybromination or oxyiodination because of the difficulty associated with the formation of chlorine cations or radicals. A transition-metal-free oxychlorination of alkenyl oximes has be
- Zhang, Xiao-Wei,Xiao, Zu-Feng,Wang, Mei-Mei,Zhuang, Yan-Jun,Kang, Yan-Biao
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p. 7275 - 7281
(2016/08/05)
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- Oxime-mediated oxychlorination and oxybromination of unactivated olefins
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An oxime-mediated oxychlorination and oxybromination of unactivated olefins relying on palladium catalysis has been developed. A wide range of chlorinated and brominated isoxazolines has been synthesized in moderate to good yields. To demonstrate the value of the method, the brominated isoxazoline has been further converted to other useful synthetic feedstock.
- Dong, Kui-Yong,Qin, Hai-Tao,Liu, Feng,Zhu, Chen
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p. 1419 - 1422
(2015/03/04)
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- Iodine(III)-Mediated Oxy-fluorination of Alkenyl Oximes: An Easy Path to Monofluoromethyl-Substituted Isoxazolines
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A highly regioselective intramolecular oxy-fluorination of alkenyl oximes was achieved. This new transformation represents an efficient method for the preparation of monofluoromethyl-substituted isoxazolines. The synthetic application of the oxy-fluorinat
- Kong, Weidong,Guo, Quanping,Xu, Zhaoqing,Wang, Guoqiang,Jiang, Xianxing,Wang, Rui
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p. 3686 - 3689
(2015/08/18)
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- Copper-catalyzed oxyazidation of unactivated alkenes: A facile synthesis of isoxazolines featuring an azido substituent
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A novel and efficient Cu(OAc)2-catalyzed oxyazidation of unactivated alkenes was developed. The reactions are easy to conduct, occur under mild conditions, and form azido-substituted isoxazolines in good yields.
- Zhu, Liping,Yu, Hongmei,Xu, Zhaoqing,Jiang, Xianxing,Lin, Li,Wang, Rui
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p. 1562 - 1565
(2014/04/17)
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- Copper-catalyzed 5-endo-trig cyclization of ketoxime carboxylates: A facile synthesis of 2-arylpyrroles
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A novel and facile copper-catalyzed 5-endo-trig cyclization of ketoxime carboxylates for the synthesis of 2-arylpyrroles has been developed. The reaction tolerates a range of functional groups and is a practical procedure for rapid synthesis of 2-arylpyrroles in high yields under mild conditions. the Partner Organisations 2014.
- Du, Wei,Zhao, Mi-Na,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
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p. 7437 - 7439
(2014/07/07)
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- Iminoxyl radical-promoted dichotomous cyclizations: Efficient oxyoximation and aminooximation of alkenes
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A novel iminoxyl radical-involved metal-free approach to vicinal oxyoximation and aminooximation of unactivated alkenes is developed. This method utilizes the dichotomous reactivity of the iminoxyl radical to furnish a general difunctionalization on alkenes using simple tert-butyl nitrite (TBN) as the iminoxyl radical initiator as well the carbon radical trap. By using this protocol, oxime featured 4,5-dihydroisoxazoles and cyclic nitrones were facilely prepared from β,γ- and γ,δ-unsaturated ketoximes, respectively.
- Peng, Xie-Xue,Deng, Yun-Jing,Yang, Xiu-Long,Zhang, Lin,Yu, Wei,Han, Bing
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p. 4650 - 4653
(2015/01/08)
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- Oxime radical promoted dioxygenation, oxyamination, and diamination of alkenes: Synthesis of isoxazolines and cyclic nitrones
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Up the tempo: The intramolecular addition of oxime radicals to C=C bonds was achieved by using DEAD and TEMPO to give 4,5-dihydroisoxazoles as a result of a C=O bond-forming, 5-exo-trig cyclization. γ,δ-Unsaturated ketoximes also reacted to afford cyclic nitrones through C-N bond formation. The reactions offer a metal-free approach for the vicinal difunctionalization of unactivated alkenes. Copyright
- Han, Bing,Yang, Xiu-Long,Fang, Ran,Yu, Wei,Wang, Chao,Duan, Xiao-Yong,Liu, Shuai
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p. 8816 - 8820
(2012/10/18)
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- Diverse alkanones by catalytic carbon insertion into the formyl C-H bond. Concise access to the natural precursor of achyrofuran
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Over a century ago, the first reactions of diazomethane with aldehydes delivered methyl ketones. In the interim, aldehydes have been homologated with trimethylsilyldiazomethane, diazoacetates, and aryldiazomethanes, on rare occasion with catalysis. This work describes a mild procedure for convergent ketone assembly from nonstabilized diazoalkanes, including examples of chiral ketone synthesis with disubstituted (internal) nucleophiles. The method's remarkable tolerance to steric crowding is showcased in a simple approach to achyrofuran, a complex dibenzofuran.
- Wommack, Andrew J.,Moebius, David C.,Travis, Austin L.,Kingsbury, Jason S.
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supporting information; experimental part
p. 3202 - 3205
(2009/11/30)
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- Iridium-catalyzed C-C coupling via transfer hydrogenation: Carbonyl addition from the alcohol or aldehyde oxidation level employing 1,3-cyclohexadiene
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Under hydrogen autotransfer conditions employing a catalyst derived from [lr(cod)CI]2 and BIPHEP, 1,3-cyclohexadiene (CHD) couples to benzylic alcohols 1a-9a to furnish carbonyl addition products 1c-9c, which appear as single diastereomers with variable quantities of regioisomeric adducts 1d-9d. Under related transfer hydrogenation conditions employing isopropanol as terminal reductant, identical carbonyl adducts 1c-9c are obtained from the aldehyde oxidation level. Isotopic labeling studies corroborate a mechanism involving hydrogen donation from the reactant alcohol or sacrificial alcohol (i-PrOH).
- Bower, John F.,Patman, Ryan L.,Krische, Michael J.
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supporting information; experimental part
p. 1033 - 1035
(2009/04/07)
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- The formation of 7-oxabicyclo[4.2.0]octanes and 6-oxabicyclo[3.2.1]octanes via cationic iodocyclization
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Several 2-cyclohexenemethanol derivatives were subjected to cationic iodocyclization. Two product types were formed: the fused 7-oxabicyclo[4.2.0]octane, and the bridged 6-oxabicyclo[3.2.1]octane. The degree of substitution in the alkenol determined the ratio of the products, with aromatic substituents leading to the formation of the fused system as the major product.
- Nichols, Christopher J.
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p. 2167 - 2179
(2007/10/03)
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- Hypervalent silane and siloxane derivatives and the use thereof
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Hypervalent silane and siloxane reagents (preformed or generated in situ) for transmetalation in palladium catalyzed reactions with derivatives of allylic alcohols, aryl halides, electron-withdrawing aryl bromides, and aryl triflates derived from phenols are disclosed. Also disclosed are methods of preparing glycosyl azides by reaction of an azide with a silyl ester in the presence of a phoshine.
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- Oxidative Cyclization of δ,ε- and ε,ζ-Unsaturated Enol Silyl Ethers and Unsaturated Siloxycyclopropanes
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Oxidative cyclization of δ,ε- and ε,ζ-unsaturated enol silyl ethers 4a and 4b with cupric triflate and cuprous oxide or ceric ammonium nitrate and sodium bicarbonate in acetonitrile provides the tricyclic ketones 5a and 5b stereoselectively.These cyclizat
- Snider, Barry B.,Kwon, Taesoo
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p. 2399 - 2410
(2007/10/02)
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- PALLADIUM-CATALYZED CROSS COUPLING OF ALLYL HALIDES WITH ORGANOTIN REAGENTS: A METHOD OF JOINING HIGHLY FUNCTIONALIZED PARTNERS REGIOSELECTIVELY AND STEREOSPECIFICALLY.
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The palladium-catalyzed reaction of allyl halides with aryl- and vinyltin reagents gives high yields of cross-coupled products. In the presence of 1-3 atm of carbon monoxide, ketones are obtained, resulting from cross coupling accompanied by carbon monoxide insertion. The reaction is mild and tolerant of a wide variety of functionalities (OH, OR, CN, CO//2R, CHO) on either the allyl chloride or the tin reagent. Coupling at the allyl halide partner proceeds with inversion of configuration at the carbon bearing the halide, with retention of geometry at the allylic double bond, and with a regioselectivity for the least-substituted carbon in the allylic framework. Retention of double-bond geometry is observed in the vinyltin partner.
- Sheffy,Godschalx,Stille
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p. 4833 - 4840
(2007/10/11)
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- Effective Method for the Conjugate Addition of γ-Acetoxy-αβ-unsaturated Ketones with RCu-AlCl3
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An efficient procedure for the conjugate addition of γ-acetoxy-αβ-unsaturated ketones with RCu-AlCl3 is described.
- Ibuka, Toshiro,Minakata, Hiroyuki,Mitsui, Yoshinori,Kinoshita, Kyoko,Kawami, Yumiko
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p. 1193 - 1194
(2007/10/02)
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