- A convenient access to allylic triflones with allenes and triflyl chloride in the presence of (EtO)2P(O)H
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A simple method for the preparation of allylic triflones from allenes and triflyl chloride in the presence of (EtO)2P(O)H has been developed. The features of this reaction are catalyst-free and simple starting substrates. This method tolerates diverse functional groups and substituted allylic triflones are obtained in moderate to good yields.
- Ni, Jixiang,Jiang, Yong,An, Zhenyu,Lan, Jingfeng,Yan, Rulong
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p. 7343 - 7345
(2019/06/27)
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- Synthesis of Functionalized α-Vinyl Aldehydes from Enaminones
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An efficient RhII-catalyzed synthesis of functionalized α-vinyl aldehydes with high E/Z stereoselectivity was developed. The reaction mediates the cyclopropanation of enaminones with vinyl carbenoids that are generated from cyclopropenes in situ to give the aminocyclopropane intermediates. Selective C?C bond cleavage of the cyclopropane intermediates leads to formation of α-vinyl aldehyde derivatives with high E/Z selectivity. This method proceeds at room temperature under very mild reaction conditions and works with a broad substrate scope.
- Chen, Jie,Guo, Pan,Zhang, Jianguo,Rong, Jiaxin,Sun, Wangbin,Jiang, Yaojia,Loh, Teck-Peng
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p. 12674 - 12679
(2019/08/07)
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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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p. 14304 - 14307
(2019/11/13)
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- Regioselective Diboron-Mediated Semireduction of Terminal Allenes
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A method for the regioselective reduction of the terminal double bond of 1,1-disubstituted allenes has been developed. In the presence of a palladium catalyst, tetrahydroxydiboron and stoichiometric water, allene semireduction proceeds in high yield to afford Z-alkenes selectively.
- Gates, Ashley M.,Santos, Webster L.
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p. 4619 - 4624
(2019/12/11)
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- Construction of All-Carbon Chiral Quaternary Centers through CuI-Catalyzed Enantioselective Reductive Hydroxymethylation of 1,1-Disubstituted Allenes with CO2
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A catalytic enantioselective construction of all-carbon chiral quaternary centers through reductive hydroxymethylation of 1,1-disubstituted allenes with CO2 has been developed. In the presence of a copper/Mandyphos catalyst, CO2 is t
- Qiu, Jia,Gao, Shen,Li, Chaopeng,Zhang, Lei,Wang, Zheng,Wang, Xiaoming,Ding, Kuiling
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supporting information
p. 13874 - 13878
(2019/11/11)
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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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p. 796 - 802
(2018/04/16)
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- Tandem Hydroalumination/Cu-Catalyzed Asymmetric Vinyl Metalation as a New Access to Enantioenriched Vinylcyclopropane Derivatives
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Herein, we report the first enantio- and diastereoselective addition of stereodefined vinyl organometallic reagents to cyclopropenes. The operationally simple tandem hydroalumination and copper-catalyzed vinylmetalation allows for the unique access of a diverse set of enantioenriched vinylcyclopropane derivatives.
- Müller, Daniel S.,Werner, Veronika,Akyol, Sema,Schmalz, Hans-Günther,Marek, Ilan
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p. 3970 - 3973
(2017/08/14)
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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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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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p. 11702 - 11705
(2017/09/07)
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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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p. 3130 - 3134
(2016/10/09)
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- Asymmetric Copper-Catalyzed Carbozincation of Cyclopropenes en Route to the Formation of Diastereo- and Enantiomerically Enriched Polysubstituted Cyclopropanes
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The enantioselective synthesis of cyclopropylzinc reagents has been achieved via a copper-catalyzed carbozincation of 3,3-disubstituted cyclopropenes with diorganozinc reagents. The obtained organozinc compounds can be easily functionalized with a broad range of electrophiles, including palladium-catalyzed cross-couplings, affording highly substituted cyclopropanes. The operationally simple procedure using very low quantities of a commercially available and inexpensive copper catalyst provides a new tool for the synthesis of highly enantioenriched cyclopropanes as single diastereoisomers.
- Müller, Daniel S.,Marek, Ilan
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supporting information
p. 15414 - 15417
(2015/12/26)
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- Preparative resolution of bromocyclopropylcarboxylic acids
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A general and efficient method for the preparative resolution of α- and β-bromocyclopropylcarboxylic acids has been developed. This protocol involves a sequence of two crystallizations with pseudo-enantiomeric amines, cinchonine, and cinchonidine, which yield both enantiomers of the acid in highly enriched form. Both alkaloids can be easily recovered and reused multiple times without any loss of efficacy.
- Edwards, Andrew,Ryabchuk, Pavel,Barkov, Alexey,Rubina, Marina,Rubin, Michael
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p. 1537 - 1549
(2015/02/02)
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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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- SELECTIVITY IN THE REACTIONS OF 3,3-DISUBSTITUTED CYCLOPROPENES WITH NITRILE OXIDES
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The reactions of 3-R-3-R'-disubstituted cyclopropenes with nitrile oxides lead to the formation of 4,6,6-trisubstituted 2-oxa-3-azabicyclohex-3-enes, which can be isolated with high yields.Substituents at C3 of the cyclopropane ring (phe
- Bolesov, I. G.,Ignatchenko, A. V.,Bovin, N. V.,Prudchenko, I. A.,Surmina, L. S.,et al.
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- REACTION OF 2,2-DISUBSTITUTED 1-(DIBROMOMETHYLENE)CYCLOPROPANES WITH METHYLLITHIUM
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In the reaction of 2,2-disubstituted 1-(dibromomethylene)cyclopropanes with methyllithium 4,4-disubstituted 1-buten-3-ynes and 2,2-disubstituted (1-bromoethylidene)cyclopropanes are formed in ratios which depend on the character of substitution in the cyclopropane ring.
- Kostikov, R. R.,Molchanov, A. P.,Nagi, Sh. M.
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p. 1291 - 1297
(2007/10/02)
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- EFFECT OF THE NATURE OF SUBSTITUENTS IN THE THREE-CARBON RING ON THE DEMETHYLATION OF p-CYCLOPROPYLANISOLES DURING NITRATION
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The behavior of a series of p-cyclopropylanisoles substituted in the small ring was investigated under conditions favoring their demethylation during nitration.It was shown that the yields of the nitrophenols which form depend on the nature and on the pos
- Mochalov, S. S.,Karpova, V. V.,Shabarov, Yu. S.
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p. 495 - 503
(2007/10/02)
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- Halocyclopropyl substituted phenoxyalkanoic acids
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Halocyclopropyl substituted phenoxyalkanoic acids and esters thereof, having hypocholesteremic activity are prepared via several alternative synthetic approaches, involving as the key reactions interaction of a substituted phenylalkene with a carbene source to introduce the halocyclopropyl moiety, and reaction of a substituted phenol with chloroform and a lower-alkanone in the presence of base, or with a lower-alkyl α-bromo-alkanoate, to form the phenoxyalkanoic acid moiety.
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