- An unusual, DDQ-promoted oxidative rearrangement of 9,9-disubstituted 1,4,5,8-tetrahydro-4a,8a-methanonaphthalenes
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The action of excess DDQ on 1,4,5,8-tetrahydro-4a,8a-methanonaphthalenes bearing a methyl group and one other substituent (cyclopropyl, methyl, phenyl) at the 9 position resulted in a peculiar oxidative rearrangement to 1-vinylnaphthalene derivatives. Two closely related mechanisms, both of which involve a 1,5-sigmatropic shift of the one-carbon bridge (Berson-Willcott rearrangement), are considered for this novel process.
- Barasz, Jonah A.,Ghaffari, Ali H.,Otte, Douglas A.,Thamattoor, Dasan M.
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Read Online
- Electrochemical fluorosulfonylation of alkenes to access vicinal fluorinated sulfones derivatives
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Herein, we report a practical and efficient fluorosulfonylation of the various alkenes with sulfonyl radical sources (RSO2NHNH2) and Et3N·3HF as cost-effective fluorination reagents under mild conditions. Remarkably, this
- Zhao, Bin,Pan, Zichen,Zhu, Anqiao,Yue, Yanni,Ma, Mengtao,Xue, Fei
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supporting information
(2022/01/24)
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- 1,3-Difunctionalization of β-alkyl nitroalkenes via combination of Lewis base catalysis and radical oxidation
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Upon treatment with a Lewis base catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylic nitro compounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent yields. This work further extended the general synthetic application of β-alkyl nitroalkenes.
- Wang, Ye,Zheng, Lei,Shi, Xiaodong,Chen, Yunfeng
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supporting information
p. 886 - 889
(2021/02/01)
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- Formal Allylation and Enantioselective Cyclopropanation of Donor/Acceptor Rhodium(II) Azavinyl Carbenes
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A highly efficient formal allylation of dihydronaphthotriazoles with alkenes under rhodium(II) catalysis is reported. Various allyl dihydronaphthalene derivatives were furnished via rhodium(II) azavinyl carbenes with moderate to good yields and excellent chemoselectivity. When monosubstituted alkenes are used, cyclopropanation occurs and good to excellent enantioselectivities have been achieved. Particularly noteworthy is the allylic C(sp2)-H activation instead of traditional C(sp3)-H activation in the formal allylation process.
- Liu, Zhili,Chen, Lianfen,Zhu, Dong,Zhu, Shifa
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supporting information
p. 1275 - 1279
(2021/02/20)
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- The cascade coupling/iodoaminocyclization reaction of trifluoroacetimidoyl chlorides and allylamines: metal-free access to 2-trifluoromethyl-imidazolines
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A metal-free cascade coupling/iodoaminocyclization reaction for the rapid assembly of 2-trifluoromethyl-imidazolines has been disclosed. The transformation applies readily accessible trifluoroacetimidoyl chlorides, allylamines andN-iodosuccinimides as the starting substrates, achieving an efficient and straightforward pathway to construct diverse imidazoline derivatives. Excellent efficiency of the reaction is observed (higher than 90% isolated yield for half of the examples), and the obtained imidazoline products bearing a pendent iodomethyl group could be easily transformed into other synthetically valuable compounds.
- Chen, Zhengkai,Du, Shiying,Song, Yufei,Wang, Le-Cheng,Wu, Xiao-Feng
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supporting information
p. 6115 - 6119
(2021/07/21)
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- Aqueous ZnCl2 Complex Catalyzed Prins Reaction of Silyl Glyoxylates: Access to Functionalized Tertiary α-Silyl Alcohols
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An efficient Prins reaction of silyl glyoxylates in the presence of an aqueous ZnCl2 complex as a catalyst was developed, providing functionalized tertiary α-silyl alcohols in high yields under mild conditions. A preliminary investigation indicated that the aqueous ZnCl2 complex acted as a dual functional catalyst of Br?nsted and Lewis acid to activate the carbonyl groups of silyl glyoxylates via a dual-activation model.
- Han, Man-Yi,Pan, Hong,Li, Pinhua,Wang, Lei
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p. 5825 - 5837
(2020/05/22)
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- Synthesis of N-Alkylpyridin-4-ones and Thiazolo[3,2- a]pyridin-5-ones through Pummerer-Type Reactions
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N-Alkylated 4-pyridones were obtained through a one-pot procedure involving either normal or interrupted Pummerer reactions between triflic anhydride-activated sulfoxides and 4-fluoropyridine derivatives, followed by hydrolysis. On the other hand, triflic anhydride-activated benzyl 6-fluoro-2-pyridyl sulfoxide could react with alkenes or alkynes to afford thiazolo[3,2-a]pyridin-5-ones, via the pyridinium salt intermediates.
- Huang, Jingjia,Hu, Gang,An, Shaoyu,Chen, Dongding,Li, Minglei,Li, Pingfan
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p. 9758 - 9769
(2019/08/08)
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- The Allylic Acetoxylation of 1,1-Disubstituted Alkenes Catalyzed by a Palladium(II)/Monothiadiazole Ligand System
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A palladium(II)/monothiadiazole ligand catalytic system and its application in catalyzing the acetoxylation of 1,1-disubstituted alkenes have been developed. With this newly designed monothiadiazole thioether ligand, the reaction showed a broad scope with respect to 1,1-disubstituted olefins, giving the corresponding products in yields of 30-86percent.
- Jin, Can,Li, Xiaohan,Sun, Bin,Wang, Jiayang,Yang, Jin,Yu, Chuangming,Zhang, Xun,Zhuang, Xiaohui
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p. 1479 - 1483
(2019/07/15)
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- Copper-Catalyzed Enantio- and Diastereoselective Addition of Silicon Nucleophiles to 3,3-Disubstituted Cyclopropenes
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A highly stereocontrolled syn-addition of silicon nucleophiles across cyclopropenes with two different geminal substituents at C3 is reported. Diastereomeric ratios are excellent throughout (d.r.≥98:2) and enantiomeric excesses usually higher than 90 %, even reaching 99 %. This copper-catalyzed C?Si bond formation closes the gap of the direct synthesis of α-chiral cyclopropylsilanes.
- Zhang, Liangliang,Oestreich, Martin
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supporting information
p. 14304 - 14307
(2019/11/13)
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- Synthesis of 2-Substituted Propenes by Bidentate Phosphine-Assisted Methylenation of Acyl Fluorides and Acyl Chlorides with AlMe3
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Bidentate phosphine-assisted methylenation of acyl fluorides and acyl chlorides with substituted with aryl, alkenyl, and alkyl groups trimethylaluminum afforded an array of 2-substituted propene derivatives. The addition of a catalytic amount of DPPM increased an efficiency of the reactions. Trimethylaluminum as the methylenation reagent not only eliminates the presynthesis of methylene transfer reagent, but provides an efficient method for the synthesis of a series of 2-substituted propenes.
- Wang, Xiu,Wang, Zhenhua,Asanuma, Yuya,Nishihara, Yasushi
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supporting information
p. 3640 - 3643
(2019/05/17)
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- Nickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones with the liberation of H2
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A nickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones to access various terminal and internal olefins with the liberation of hydrogen gas is reported.
- Landge, Vinod G.,Yadav, Vinita,Subaramanian, Murugan,Dangarh, Pragya,Balaraman, Ekambaram
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supporting information
p. 6130 - 6133
(2019/06/03)
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- Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: Synthesis of vicinal-dichlorides and chlorodienes
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Allyl and vinyl chlorides represent important structural motifs in organic chemistry. Herein is described the chemoselective and regioselective reaction of aryl- and α-substituted phenylallenes with the hypervalent iodine (HVI) reagent 1-chloro-1,2-benz-iodoxol-3-one. The reaction typically results in vicinal dichlorides, except with proton-containing α-alkyl substituents, which instead give chlorinated dienes as the major product. Experimental evidence suggests that a radical mechanism is involved.
- Zhao, Zhensheng,Murphy, Graham K.
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supporting information
p. 796 - 802
(2018/04/16)
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- Discovery of flexible naphthyltriazolylmethane-based thioacetic acids as highly active uric acid transporter 1 (URAT1) inhibitors for the treatment of hyperuricemia of gout
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Background: Gout is the most common inflammatory arthritis, which, if left untreated or inadequately treated, will lead to joint destruction, bone erosion and disability due to the crystal deposition. Uric acid transporter 1 (URAT1) was the promising therapeutic target for urate-lowering therapy. Objective: The goal of this work is to understand the structure-activity relationship (SAR) of a potent lesinurad-based hit, sodium 2-((5-bromo-4-((4-cyclopropyl-naphth-1-yl)methyl)-4H-1,2,4-triazol-3-yl)thio)acetate (1c), and based on that discover a more potent URAT1 inhibitor. Methods: The SAR of 1c was systematically explored and the in vitro URAT1 inhibitory activity of synthesized compounds 1a-1t was determined by the inhibition of URAT1-mediated [8-14C]uric acid uptake by human embryonic kidney 293 (HEK293) cells stably expressing human URAT1. Results: Twenty compounds 1a-1t were synthesized. SAR analysis was performed. Two highly active URAT1 inhibitors, sodium 2-((5-bromo-4-((4-n-propylnaphth-1-yl)methyl)-4H-1,2,4-triazol-3-yl)thio)acetate (1j) and sodium 2-((5-bromo-4-((4-bromonaphth-1-yl)methyl)-4H-1,2,4-triazol-3-yl)thio)acetate (1m), were identified, which were 78- and 76-fold more active than parent lesinurad in in vitro URAT1 inhibitory assay, respectively (IC50 values for 1j and 1m were 0.092 μM and 0.094 μM, respectively, against human URAT1 vs 7.18 μM for lesinurad). Conclusion: Two highly active URAT1 inhibitors were discovered. The SAR exploration also identified more flexible naphthyltriazolylmethane as a novel molecular skeleton that will be valuable for the design of URAT1 inhibitors, as indicated by the observation that many of the synthesized naphthyltriazolylmethane-bearing derivatives (1b-1d, 1g, 1j and 1m) showed significantly improved UART1 inhibitory activity (sub-micromolar IC50 values) as compared with lesinurad which has the rigid naphthyltriazole skeleton.
- Zhang, Xiansheng,Wu, Jingwei,Liu, Wei,Liu, Yuqiang,Xie, Yafei,Shang, Qian,Zhou, Zhixing,Xu, Weiren,Tang, Lida,Wang, Jianwu,Zhao, Guilong
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p. 260 - 281
(2017/05/31)
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- Fluorinative Rearrangements of Substituted Phenylallenes Mediated by (Difluoroiodo)toluene: Synthesis of α-(Difluoromethyl)styrenes
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Phenylallenes undergo fluorinative rearrangement upon the action of (difluoroiodo)toluene in the presence of 20 mol % BF3?OEt2 to yield α-difluoromethyl styrenes. This unprecedented reaction was entirely chemoselective for the internal allene π bond, and showed remarkable regioselectivity during the fluorination event. Substituted phenylallenes, phenylallenes possessing both phenyl- and α-allenyl substituents, and diphenylallenes were investigated, and good functional-group compatibility was observed throughout. The ease with which allenes can be prepared on a large scale, and the operational simplicity of this reaction allowed us to rapidly access fluorine-containing building blocks that have not been accessed by conventional deoxyfluorination strategies.
- Zhao, Zhensheng,Racicot, Léanne,Murphy, Graham K.
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supporting information
p. 11620 - 11623
(2017/09/11)
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- Asymmetric Nitrone Synthesis via Ligand-Enabled Copper-Catalyzed Cope-Type Hydroamination of Cyclopropene with Oxime
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We report realization of the first enantioselective Cope-type hydroamination of oximes for asymmetric nitrone synthesis. The ligand promoted asymmetric cyclopropene "hydronitronylation" process employs a Cu-based catalytic system and readily available starting materials, operates under mild conditions and displays broad scope and exceptionally high enantio- and diastereocontrol. Preliminary mechanistic studies corroborate a CuI-catalytic profile featuring an olefin metalla-retro-Cope aminocupration process as the key C-N bond forming event. This conceptually novel reactivity enables the first example of highly enantioselective catalytic nitrone formation process and will likely spur further developments that may significantly expedite chiral nitrone synthesis.
- Li, Zhanyu,Zhao, Jinbo,Sun, Baozhen,Zhou, Tingting,Liu, Mingzhu,Liu, Shuang,Zhang, Mengru,Zhang, Qian
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supporting information
p. 11702 - 11705
(2017/09/07)
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- Palladium-catalyzed oxidative allylation of bis[(pinacolato)boryl]methane: Synthesis of homoallylic boronic esters
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A palladium-catalyzed oxidative allylation of bis[(pinacolato)boryl]methane to afford the corresponding homoallylic organoboronic esters with moderate to excellent yields is reported. This novel transformation provides an efficient strategy for the construction of homoallylic organoboronic esters in one step with a broad substrate scope. It is proposed that the palladium-catalyzed oxidative allylic C-H bond activation process may be involved in the catalytic cycle.
- Li, Chunsheng,Li, Meng,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 66 - 69
(2017/12/27)
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- Iodothiocyanation/Nitration of Allenes with Potassium Thiocyanate/Silver Nitrite and Iodine
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Direct strategies for the iodothiocyanation and iodonitration of allenes have been developed. In this process, potassium thiocyanate/silver nitrite and molecular iodine are used as the source of SCN, ONO2and iodine to provide the desired products in moderate to good yields with high stereoselectivity. (Figure presented.).
- Yang, Xiaodong,She, Yue,Chong, Ya,Zhai, Huichun,Zhu, He,Chen, Baohua,Huang, Guosheng,Yan, Rulong
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supporting information
p. 3130 - 3134
(2016/10/09)
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- Mn-Catalyzed Highly Efficient Aerobic Oxidative Hydroxyazidation of Olefins: A Direct Approach to β-Azido Alcohols
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(Chemical Equation Presented). An efficient Mn-catalyzed aerobic oxidative hydroxyazidation of olefins for synthesis of β-azido alcohols has been developed. The aerobic oxidative generation of azido radical employing air as the terminal oxidant is disclosed as the key process for this transformation. The reaction is appreciated by its broad substrate scope, inexpensive Mn-catalyst, high efficiency, easy operation under air, and mild conditions at room temperature. This chemistry provides a novel approach to high value-added β-azido alcohols, which are useful precursors of aziridines, β-amino alcohols, and other important N- and O-containing heterocyclic compounds. This chemistry also provides an unexpected approach to azido substituted cyclic peroxy alcohol esters. A DFT calculation indicates that Mn catalyst plays key dual roles as an efficient catalyst for the generation of azido radical and a stabilizer for peroxyl radical intermediate. Further calculation reasonably explains the proposed mechanism for the control of C-C bond cleavage or for the formation of β-azido alcohols.
- Sun, Xiang,Li, Xinyao,Song, Song,Zhu, Yuchao,Liang, Yu-Feng,Jiao, Ning
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supporting information
p. 6059 - 6066
(2015/05/27)
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- Iridium-Catalyzed Enantioselective Hydrogenation of β,β-Disubstituted Nitroalkenes
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A highly efficient, iridium-catalyzed, enantioselective hydrogenation of β,β-disubstituted nitroalkenes has been developed. Using a complex consisting of iridium and (S,S)-f-spiroPhos as the catalyst, a variety of β,β-disubstituted nitroalkenes were successfully hydrogenated to the corresponding chiral nitroalkanes with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON=1000).
- Liu, Man,Kong, Duanyang,Li, Meina,Zi, Guofu,Hou, Guohua
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supporting information
p. 3875 - 3879
(2016/01/25)
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- Nickel-catalyzed Kumada reaction of tosylalkanes with Grignard reagents to produce alkenes and modified arylketones
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Open a new door: The first example of alkene synthesis from alkyl electrophiles with Grignard reagents using the Kumada cross-coupling reaction strategy is reported. This method opens a new door for the Kumada cross-coupling reaction, allowing alkenes to be prepared from the reaction of tosylalkanes with Grignard reagents. Copyright
- Wu, Ji-Cheng,Gong, Lu-Bing,Xia, Yuanzhi,Song, Ren-Jie,Xie, Ye-Xiang,Li, Jin-Heng
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supporting information
p. 9909 - 9913
(2012/10/30)
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- Chemoselective transfer of allyl or phenyl group from allyl(phenyl)germanes in Pd-catalyzed reactions with aryl halides
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Treatment of chloro(phenyl)germanes with allylmagnesium bromide yielded allyl(phenyl)germanes. Coupling of the allyl- (phenyl)germanes with aryl halides in 1,4-dioxane in the presence of aqueous NaOH and Pd catalyst resulted in Heck-type transfer of the allyl group providing the corresponding allylated aryls. On the other hand, reaction of allyl(phenyl)germanes with SbF5 intercalated in graphite in toluene and subsequent treatment of the resulting germanyl fluorides with TBAF generates reactive hypervalent fluorogermanates that undergo Stille-like Pd-catalyzed cross-coupling with aryl halides in wet toluene to provide biaryls.
- Pitteloud, Jean-Philippe,Liang, Yong,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 967 - 969
(2011/12/05)
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- Nickel-catalyzed heck-type reactions of benzyl chlorides and simple olefins
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Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives are described. A wide range of both the benzyl chloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including ethylene), proceed at room temperature, and provide 1,1-disubstituted olefins over the more commonly observed 1,2-disubstituted olefins with very high selectivity.
- Matsubara, Ryosuke,Gutierrez, Alicia C.,Jamison, Timothy F.
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supporting information; experimental part
p. 19020 - 19023
(2011/12/21)
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- Improved preparative route toward 3-arylcyclopropenes
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A convenient preparative protocol for the synthesis of various 3-arylcyclopropenes in a multigram scale is disclosed. Optimization of the reaction conditions and isolation procedures allowed for significant improvement of the chemical yields of these strained products. The described protocol was used for efficient preparation of a series of 3-methyl-3-arylcyclopropenes possessing different substituents in the aromatic ring. The effect of substitution in the aryl group on the stability of 3-arylcyclopropenes, as well as the corresponding precursors, is discussed.
- Sherrill, William M.,Kim, Ryan,Rubin, Michael
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p. 8610 - 8617
(2008/12/21)
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- Unusual inhibition effect of 1-(1-naphthyl)-1-methylethylhydroperoxide on the liquid-phase oxidation of isopropylarenes. GC-MS and theoretical studies of the thermal decomposition of 1-naphthyl- and 1-anthryl-1- methylethylhydroperoxides
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All five possible 1-aryl-1methylethylhydroperoxides derived from naphthalene and anthracene were synthesized and their thermal decomposition in GC-MS conditions was investigated to explain the unusual inhibition effect of 1-(1-naphthyl)-1-methylethylhydroperoxide on the liquid-phase oxidation of isopropylarenes. 2-(1-Aryloxy)propenes were identified as the main decomposition products of 1-(1-naphthyl)-1-methylethylhydroperoride and 1-(1-anthryl)-1- methylethylhydroperoxide. The relatively unstable 2-aryloxypropenes have thus far never been described as thermal decomposition products of 1-aryl-1-methylethylhydroperoxides. The plausible mechanism of the formation of 2-(1-aryloxy)propenes was proposed on the basis of AM-1 calculations of the possible rearrangement paths of the alkoxy radicals derived from the investigated hydroperoxides. The mechanism explains the inhibition effect of 1-(1-naphthyl)-1-methylethylhydroperoxide on the oxidation of isopropylarenes.
- Mazurkiewicz, Roman,Zawadiak, Jan,Orlinska, Beata,Hefczyc, Barbara,Stec, Zbigniew,Grymel, Miroslawa,Fiedorow, Piotr,Koroniak, Henryk
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p. 289 - 295
(2012/12/22)
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- Suzuki cross-coupling reactions between alkenylboronic acids and aryl bromides catalysed by a tetraphosphane-palladium catalyst
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A range of alkenylboronic acids undergo Suzuki cross-coupling with aryl bromides in good yields in the presence of [PdCl(C3H 5)]2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphanyl) methyl]cyclopentane as a catalyst. A wide variety of 1-arylprop-1-enes, 2-arylprop-1-enes, 2-arylbut-1-enes and 1,1-diarylethylene or styrene derivatives have been prepared. Moreover, the reaction tolerates several functions, such as acetyl, formyl, nitrile or nitro. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Peyroux, Eugenie,Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 1075 - 1082
(2007/10/03)
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- Cobalt-catalyzed electrochemical vinylation of aryl halides using vinylic acetates
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The electroreduction of aryl halides (bromides or chlorides) allows the coupling reaction with vinylic acetates, in the presence of 2,2-bipyridine and catalytic amounts of cobalt bromide, leading to styrene derivatives in good yields.
- Gomes, Paulo,Gosmini, Corinne,Périchon, Jacques
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p. 2999 - 3002
(2007/10/03)
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- 5,6,7,12-Tetrahydrodibenz[c,f][1,5]azabismocines: Highly reactive and recoverable organo-bismuth reagents for cross-coupling reactions with Aryl Bromides
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Hypervalent organobismuth compounds efficiently couple with aryl bromides in the presence of [Pd(PPh3)4] catalyst. Application of this protocol to a one-pot multi-coupling reaction with bromophenylboronic esters leads to the formation of up to nine bonds in good yields (see scheme).
- Shimada, Shigeru,Yamazaki, Osamu,Tanaka, Toshifumi,Rao, Maddali L. N.,Suzuki, Yohichi,Tanaka, Masato
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p. 1845 - 1848
(2007/10/03)
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- Synthesis of polysubstituted alkenes by Heck vinylation or Suzuki cross-coupling reactions in the presence of a tetraphosphane-palladium catalyst
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Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3, 4-tetrakis[(diphenylphosphanyl)methyl]cyclopentane as a catalyst, a range of vinyl bromides undergo Suzuki cross-couplings with arylboronic acids in good yields. Furthermore, the catalyst can be used at low loadings, even for reactions of sterically hindered substrates. Mediated by this catalyst, stilbene and 1,1-diphenylethylene undergo Heck reactions with aryl halides to give triarylethylene derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 1091 - 1096
(2007/10/03)
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- 1-methyl-1-vinyl- and 1-methyl-1-(prop-2-enyl)silacyclobutane: Reagents for palladium-catalyzed cross-coupling reactions of aryl halides
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1-Methyl-1-vinylsilacyclobutane (1) and 1-methyl-1(prop-2- enyl)silacyclobutane (2) undergo rapid and high yielding cross-coupling with aromatic halides. Many different substituents and patterns on the aromatic moiety are tolerated. All reactions can be r
- Denmark, Scott E.,Wang, Zhigang
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p. 999 - 1003
(2007/10/03)
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- Oxocarbons and related compounds. Part 28. Polycycle-fused dihydrobenzocyclobutenediones and benzocyclobutenediones. Synthesis of cyclobuta[c]- and cyclobuta[a]-phenanthrene-1,2-diones and cyclobuta[a]triphenylene-11,12-dione
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The Diels-Alder reaction of semisquaric chloride 5 with 1-(alk-1-enyl)naphthalenes, 2-(alk-1-enyl)naphthalenes and 9-vinylphenanthrene is used to prepare dihydrocyclobuta[c]phenanthrene-1,2-diones 8a-c, dihydrocyclobuta[a]phenanthrene-1,2-diones 12a-c, and dihydrocyclobuta[a]triphenylene-11,12-dione 18, respectively. Treatment of the dihydrocyclobutaarenediones with bromine effects aromatization and opens up a route for the synthesis of cyclobuta[c]phenanthrene-1,2-diones 9a-c, cyclobuta[a]phenanthrene-1,2-diones 13a-c and cyclobuta[a]triphenylene-11,12-dione 19. The range of Diels-Alder reactions with semisquaric chloride 5 is extended to the use of 4-(prop-1-enyl)-1,2-dihydronaphthalene 14. Tetrahydrocyclobuta[a]phenanthrene-1,2-dione 15 is obtained in 69% yield, which can be oxidized, stepwise or at once, to give cyclobuta[a]phenanthrene-1,2-dione 13b in good yields.
- Schmidt, Arthur H.,Kircher, Gunnar,Zylla, Joerg,Veit, Stephan
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p. 409 - 414
(2007/10/03)
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- Use of carbonallation of allenes in the synthsis of polycyclic compound. A rapid access to steroid skeletons
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The carbonallation of allenes in the presence of a 1,3-cycloalkanedione enolete leads, in certain cases with good yields, to 2-substituted 1,3-cycloalkanediones with an unsaturated chain with a 1,3-butadienyl moiety (compounds 1). Under acidic conditions, these compounds can be readily cyclized with the formation of a cyclohexane ring if the substituents of the butadienyl framework exert sufficient stabilization on the electrodeficient carbon of the transition state. This methodology leads in a two-step sequence to steroids with an aromatic A-ring. Elsevier,.
- Gauthier, Veronique,Gazes, Bernard,Gore, Jacques
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p. 563 - 579
(2007/10/03)
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- Trithioorthoesters and Tetrathioorthocarbonates as RC(3+) and C(4+) Synthons. Nickel-Catalyzed Alkylative Olefination of Trithioorthoesters and Tetrathioorthocarbonates
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NiCl2(PPh3)2-catalyzed alkylative olefinations of trithioorthoesters and tetrathioorthocarbonates give the corresponding substituted alkenes.Aliphatic C-S bonds in these substrates can be activated in the nickel-catalyzed cross coupling reaction leading to carbon-carbon bond formation.This reaction can be considered as using trithiorthoesters and tetrathioorthocarbonate as R3C(3+) and C(4+) synthons. - Keywords: Trithioorthoesters, Tetrathioorthocarbonate, Nickel-Catalyzed Alkylative Olefination, Synthons of RC(3+) and C(4+)
- Tzeng, Yih-Ling,Cheng, Wen-Lung,Luh, Tien-Yau
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p. 385 - 393
(2007/10/02)
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- Lipase-catalyzed hydrolysis of some racemic 1-acetoxy-2-arylpropanes
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Racemic 1-acetoxy-2-phenylpropane (12) and 1-acetoxy-2-(2- naphthyl)propane (33) were hydrolyzed with lipase at 35-36°C for 2 and 24 h to give predominantly (S)-2-phenyl-1-propanol (11) and (S)-2-(2-naphthyl)-1- propanol (32), respectively. However, racemic 1-acetoxy-2-(1-naphthyl)propane (25) was recovered intact even when the reaction was carried out for 240 h. On the other hand, the enantioselectivities towards racemic 2-phenyl (16), 2- (p-tolyl) (20), 2-(1-naphthyl) (28), and 2-(2-naphthyl) (36) derivatives of 1-acetoxy-2-propanol were very low.
- Matsumoto,Takeda,Iwata,Sakamoto,Ishida
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p. 1191 - 1197
(2007/10/02)
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- Nickel-catalysed Alkylative Alkenation of Orthothioesters with Grignard Reagents; a Convenient Procedure for introducing the Isopropenyl Group. Synthesis of Substituted 1,3-(Bis-trimethylsilyl)propenes
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Nickel-catalysed coupling of orthothioesters with MeMgI furnishes a general method for introducing the isopropenyl group; the application of this reaction to the synthesis of 1,3-(bis-trimethylsilyl)propenes is presented.
- Tzeng, Yih-Ling,Luh, Tien-Yau,Fang, Jim-Min
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p. 399 - 400
(2007/10/02)
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- DIRECT PREPARATION OF SUBSTITUTED OLEFINS FROM EPOXIDES UTILIZING LITHIUM TETRAALKYLCERATE
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Alkylated olefins were directly synthesized in good yields by the deoxygenation reaction of epoxides with concomitant introduction of the alkyl group using lithium tetraalkylcerate.Styreneoxide and (1-naphtyl)ethyleneoxide gave terminal olefins, while ethyleneoxide replaced by alphatic substituent, 1,2-epoxy-4-phenylbutane, afforded internal olefin.The utility of the present method was demonstrated in the one-step synthesis of a sesquiterpene, dehydro-α-curcumene.
- Ukaji, Yutaka,Fujisawa, Tamotsu
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p. 5165 - 5168
(2007/10/02)
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- Kinetics and Regioselectivity of the Autoxidation of o-Substituted Isopropyl Aromatics
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The relative chain propagation constants and the regioselectivities of the oxidations of o-cymene and 2-isopropyl-1,4-dimethylbenzene were determined by competitive oxidations of the hydrocarbons with cumene.As expected, the reactivity of the tertiary C-H bond of the isopropyl group is considerably decreased by o-methyl groups.Also in α-isopropylnaphthalene a considerable decrease in the reactivity of the tertiary C-H bond takes place.The decrease of the chain propagation constants effects a decrease of the oxidabilities of o-substituted isopropyl aromatics.In the case of the methyl isopropyl benzenes the increase of the chain termination constants by primary peroxy radicals must also be taken into consideration.This results in a decrease of the oxidabilities which can be observed even in p-cymene (in comparison with cumene).
- Heinze, Antje,Lauterbach, Gerlinde,Pritzkow, Wilhelm,Schmidt-Renner, Wolfgang,Voerckel, Volkmar,Zewegsuren, Nansadyn
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p. 439 - 446
(2007/10/02)
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- Reaction of 2-Aryl-3-(N,N-dimethylamino)-1-propenes and Their Corresponding Quaternary Ammonium Salts with Organometallic Species and Reducing Agents
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A series of 2-aryl-3-(N,N-dimethylamino)-1-propenes and their corresponding quaternary ammonium salts were reacted with a variety of organometallic species and reducing agents.The utility of such reactions for the preparation of α-substituted styrene derivatives is discussed.
- Gupton, John T.,Layman, William J.
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p. 3683 - 3686
(2007/10/02)
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- THERMAL HETEROCYCLIZATION OF METHYL ARYL KETAZINES. REACTIONS OF THE TAUTOMERIC ENEHYDRAZINE FORM
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Over the temperature range 220-280 deg C the thermal reactions of methyl aryl ketazines (Ar=C6H5-, 4-CH3C6H4-, 4-CH3OC6H4-, and α-naphthyl-) proceed with their cyclization to give pyrazoline and benzodiazepine derivatives.With an increase in temperature to 320-350 deg C the subsequent transformations of these compounds lead to the formation of substituted pyrazoles, 1-methyl-1,2-diarylcyclopropanes isomeric olefins, low-molecular-weight aromatic hydrocarbons, and isoquinolines.
- Shurukhin, Yu. V.,Klyuev, N. A.,Grandberg, I. I.
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p. 723 - 732
(2007/10/02)
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- Triplet State of α-Naphthylethylene Derivatives. Structural Effects on the Equilibrium between Planar and Perpendicular Triplet Conformations
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The properties of the triplet state of a series of 1-(α-naphthyl)ethylene derivatives have been studied by laser flash photolysis.The geometry of the triplet state has been determined from the T-T absorption spectra, the lifetime values, and the quenching rate constants by oxygen, stilbene, and ferrocene.The triplet state can be either planar (nontwisted double bond), when the ethylenic moiety is inserted into a small ring, or perpendicular (double bond twisted by 90 deg), when the planar geometry is disfavored by a strong steric hinderance.However, in most cases, there is a fast equilibrium between the planar and perpendicular triplets.These two geometries are very close in energy and therefore the equilibrium can be greatly modified by small changes in the molecular structure such as an alkyl substitution.By comparison of the triplet state of 1-(α-naphthyl)-1-phenylethylene with that of other 1-aryl-1-phenylethylenes, an experimental correlation is found between the percentage of planar triplet and the triplet energy of the aryl group.
- Lazare, Sylvain,Bonneau, Roland,Lapouyade, Rene
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