- Synthesis of Quinolines via the Metal-free Visible-Light-Mediated Radical Azidation of Cyclopropenes
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We report the synthesis of quinolines using cyclopropenes and an azidobenziodazolone (ABZ) hypervalent iodine reagent as an azide radical source under visible-light irradiation. Multisubstituted quinoline products were obtained in 34-81% yield. The reaction was most efficient for 3-trifluoromethylcyclopropenes, affording valuable 4-trifluoromethylquinolines. The transformation probably proceeds through the cyclization of an iminyl radical formed by the addition of the azide radical on the cyclopropene double bond, followed by ring-opening and fragmentation.
- Smyrnov, Vladyslav,Muriel, Bastian,Waser, Jerome
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p. 5435 - 5439
(2021/07/21)
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- Rhodium-Catalyzed Intermolecular Cyclopropanation of Benzofurans, Indoles, and Alkenes via Cyclopropene Ring Opening
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The generation of metal carbenoids via ring opening of cyclopropenes by transition metals offers a simple entry into highly reactive intermediates. Herein, we describe a diastereoselective intermolecular rhodium-catalyzed cyclopropanation of heterocycles and alkenes using cyclopropenes as carbene precursors with a low loading of a commercially available rhodium catalyst. The reported method is scalable and could be performed with catalyst loadings as low as 0.2 mol %, with no impact to the reaction yield or selectivity.
- Jeyaseelan, Rubaishan,Lautens, Mark,Ross, Rachel J.
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- Stereoselective Synthesis of Vinylcyclopropa[ b]indolines via a Rh-Migration Strategy
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A mild rhodium catalytic system has been developed to synthesize vinylcyclopropa[b]indolines through cyclopropanation of indoles with vinyl carbenoids generated from ring opening of cyclopropenes in situ. By employing a Rh-migration strategy, the products can be obtained with good to excellent E:Z ratios (≤99:1) and complete diastereoselectivity (≤99:1). This method is easy, has a low catalyst loading, and works for a broad range of functionalities.
- Guo, Pan,Sun, Wangbin,Liu, Yu,Li, Yong-Xin,Loh, Teck-Peng,Jiang, Yaojia
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p. 5978 - 5983
(2020/08/05)
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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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- 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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- Rh(II)-Catalyzed [2,3]-Sigmatropic Rearrangement of Sulfur Ylides Derived from Cyclopropenes and Sulfides
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(Chemical Equation Presented) A new type of Rh2(OAc)4-catalyzed [2,3]-sigmatropic rearrangement of sulfur ylides is reported. A series of cyclopropenes were successfully employed for [2,3]-sigmatropic rearrangement by a reaction with either allylic or propargylic sulfides. Under the optimized conditions, the reaction afforded the products in moderate to excellent yields. In these transformations, the vinyl metal carbenes generated in situ from the cyclopropenes were effectively trapped by sulfides, resulting in the formation of corresponding products upon [2,3]-sigmatropic rearrangements.
- Zhang, Hang,Wang, Bo,Yi, Heng,Zhang, Yan,Wang, Jianbo
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p. 3322 - 3325
(2015/07/15)
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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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p. 15414 - 15417
(2015/12/26)
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- Rhodium-catalyzed polymerization of 3,3-diarylcyclopropenes involving a 1,4-rhodium migration
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A new mode of metal-catalyzed polymerization reaction has been developed by exploiting the ability of 1,4-rhodium migration of an organorhodium(I) species. Specifically, it has been demonstrated that 3,3-diarylcyclopropenes undergo polymerization through
- Shintani, Ryo,Iino, Ryo,Nozaki, Kyoko
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p. 7849 - 7852
(2014/06/23)
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- Enantioselective palladium-catalyzed carbozincation of cyclopropenes
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A highly enantioselective palladium-catalyzed carbozincation of cyclopropenes has been developed. The intermediate cyclopropylzinc species, after transmetalation with copper, were trapped with various electrophiles. This one-pot procedure furnished functionalizied cyclopropenes with excellent diastereo-and enantioselectivity.
- Kraemer, Katja,Leong, Paul,Lautens, Mark
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p. 819 - 821
(2011/04/24)
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- New complexes of platinum(0) with cyclopropenes
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New cyciopropene complexes of platinum have been synthesised with a variety of bulky substituents on all positions of the cyciopropene ring. Two of these novel complexes, [Pt(3,3-Ph3C3H2)(PPh3)2] and [Pt(1,2-Ph2C3H2)(PPh3)2J, have been structurally characterised by X-ray analysis. Both contain a cyciopropene ring which has remained intact upon complexation. The bond lengths within the complexes are remarkably independent of the substituents. The structural characteristics and the 31P NMR spectra of these complexes are discussed in detail.
- Hughes, David L.,Leigh, G. Jeffery,McMahon, C. Niamh
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p. 1301 - 1307
(2007/10/03)
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- The Preparation and Lithiation of 3,3-Diphenyl-1,1,2-tribromocyclopropane
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3,3-Diphenyl-1,1,2-tribromocyclopropane 4 was synthesized from benzophenone in three steps in an overall yield of 11.4percent.Treatment of 4 with buthyllithium in THF at low temperatures, generated 1-lithio- and 1,2-dilithiocyclopropenes which were charac
- Li, Gang,Warner, Philip M.
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p. 8573 - 8576
(2007/10/02)
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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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