17955-08-7Relevant articles and documents
Cyclopropyl alkynes as mechanistic probes to distinguish between vinyl radical and ionic intermediates
Gottschling, Stephen E.,Grant, Tina N.,Milnes, Kaarina K.,Jennings, Michael C.,Baines, Kim M.
, p. 2686 - 2695 (2005)
(Chemical Equation Presented) The reactions of (trans-2-phenylcyclopropyl) ethyne, 1a, (trans,trans-2-methoxy-3-phenylcyclopropyl)-ethyne, 1b, and (trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)ethyne, 1c, with either aqueous sulfuric acid or tris(trimethylsilyl)silane (or tributyltin hydride) and AIBN have been investigated. Protonation and addition of the silyl (or stannyl) radical occurred at the terminal position of the alkyne giving an α-cyclopropyl-substituted vinyl cation or radical, respectively. Under both reaction conditions, 1a yielded products derived from ring opening toward the phenyl substituent. Alkynes 1b and 1c, however, gave different products depending on whether radical or cationic conditions were used. When radical conditions were employed, products derived from regioselective ring opening toward the phenyl substituent were obtained. In contrast, when cationic conditions were employed, products derived from selective ring opening toward the methoxy substituent were isolated. The corresponding α-cyclopropyl- substituted vinyllithium derivatives were also synthesized and were found to be stable toward rearrangement. An estimate of the rate constants for ring opening of the α-cyclopropylvinyl cations was also made: values of 10 10-1012 s-1 were found for the vinyl cations derived from protonation of the terminal carbon of alkynes 1a-c. Based on these results, cyclopropyl alkynes 1a-c can be classified as hypersensitive mechanistic probes for the detection of vinyl radical or cationic intermediates generated adjacent to the cyclopropyl ring and, in the case of 1b and 1c, the distinction between a radical or cationic intermediate is possible.
Erratum: Cu-Catalyzed Three-Component Carboamination of Alkenes (J. Am. Chem. Soc. (2018) 140:1 (58?61) DOI: 10.1021/jacs.7b10529)
Gockel, Samuel N.,Buchanan, Travis L.,Hull, Kami L.
supporting information, p. 6019 - 6020 (2021/05/13)
Pages 59 and 60. We have identified an error in the structural analysis of compounds presented in our publication detailing. (Table presented).
Enantioselective Copper-Catalyzed 1,5-Cyanotrifluoromethylation of Vinylcyclopropanes
Zhang, Zi-Qi,Meng, Xiang-Yu,Sheng, Jie,Lan, Quan,Wang, Xi-Sheng
, p. 8256 - 8260 (2019/10/16)
A copper-catalyzed enantioselective 1,5-cyanotrifluoromethylation of vinylcyclopropanes has been developed using a radical relay strategy. This asymmetric reaction has demonstrated high enantioselective control, broad substrate scope, and mild conditions. Initiated by the in situ generated CF3 radical from Togni's reagent, this method offers a new solution for remote enantioselective bifunctionalization of alkenes and thus provides a straightforward way for the synthesis of chiral CF3-containing internal alkenylnitriles.
Copper-Catalyzed Oxyboration of Unactivated Alkenes
Itoh, Taisuke,Matsueda, Takumi,Shimizu, Yohei,Kanai, Motomu
supporting information, p. 15955 - 15959 (2015/11/03)
The first regiodivergent oxyboration of unactivated terminal alkenes is reported, using copper alkoxide as a catalyst, bis(pinacolato)diboron [(Bpin)2] as a boron source, and (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) as an oxygen source. The reaction is compatible with various functional groups. Two regioisomers are selectively produced by selecting the appropriate ligands on copper. The products may be used as a linchpin precursor for various other functionalizations, and net processes such as carbooxygenation, aminooxygenation, and dioxygenation of alkenes can be achieved after C-B bond transformations. Mechanistic studies indicate that the reaction involves the following steps: 1)Transmetalation between CuOtBu and (Bpin)2 to generate a borylcopper species; 2)regiodivergent borylcupration of alkenes; 3) oxidation of the thus-generated C-Cu bond to give an alkyl radical; 4)trapping of the resulting alkyl radical by TEMPO.
