3282-18-6Relevant academic research and scientific papers
Supported rhodium-catalysts: new aspects in the formation of trisubstituted olefins from simple alkenes and diazoalkanes
Werner, H.,Moehring, U.
, p. 277 - 282 (1994)
During attempts to prepare square-planar rhodium carbene complexes, a new catalytical reaction of C-C bond formation was discovered.Further investigations have shown a catalytic activity of various rhodium(I) complexes in the formation of trisubstituted o
Oxidative addition of a strained C-C bond onto electron-rich rhodium(I) at room temperature
Masuda, Yusuke,Hasegawa, Maki,Yamashita, Makoto,Nozaki, Kyoko,Ishida, Naoki,Murakami, Masahiro
, p. 7142 - 7145 (2013)
The C-C bond of cyclobutanones undergoes oxidative addition to a T-shape rhodium(I) complex possessing a PBP pincer ligand at room temperature. The remarkable propensity of the rhodium complex for oxidative addition is attributed to the highly electron-donating nature of the boron ligand as well as the unsaturation on the rhodium center.
Intermolecular Electrophilic Bromoesterification and Bromoetherification of Unactivated Cyclopropanes
Leung, Vincent Ming-Yau,Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
supporting information, p. 2039 - 2044 (2020/04/20)
1,3-difunctionalization of cyclopropane is an useful organic transformation. The corresponding 1,3-difunctionalized products are synthetic synthons and building blocks in many organic syntheses. Many existing ring-opening difunctionalization methodologies rely primarily on the use of donor?acceptor cyclopropanes, while the difunctionalization of unactivated cyclopropanes is less exploited. In this research, 1,3-bromoesterification and 1,3-bromoetherification of unactivated cyclopropanes were successfully achieved using N-bromosuccinimide as the brominating agent with high yields and regioselectivity. (Figure presented.).
Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations
Svec, Riley L.,Hergenrother, Paul J.
supporting information, p. 1857 - 1862 (2019/12/27)
Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.
Copper-Catalyzed Enantio- and Diastereoselective Addition of Silicon Nucleophiles to 3,3-Disubstituted Cyclopropenes
Zhang, Liangliang,Oestreich, Martin
supporting information, p. 14304 - 14307 (2019/11/13)
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.
Redox-Neutral Photocatalytic Cyclopropanation via Radical/Polar Crossover
Phelan, James P.,Lang, Simon B.,Compton, Jordan S.,Kelly, Christopher B.,Dykstra, Ryan,Gutierrez, Osvaldo,Molander, Gary A.
supporting information, p. 8037 - 8047 (2018/07/03)
A benchtop stable, bifunctional reagent for the redox-neutral cyclopropanation of olefins has been developed. Triethylammonium bis(catecholato)iodomethylsilicate can be readily prepared on multigram scale. Using this reagent in combination with an organic photocatalyst and visible light, cyclopropanation of an array of olefins, including trifluoromethyl- and pinacolatoboryl-substituted alkenes, can be accomplished in a matter of hours. The reaction is highly tolerant of traditionally reactive functional groups (carboxylic acids, basic heterocycles, alkyl halides, etc.) and permits the chemoselective cyclopropanation of polyolefinated compounds. Mechanistic interrogation revealed that the reaction proceeds via a rapid anionic 3-exo-tet ring closure, a pathway consistent with experimental and computational data.
A Modular Approach to the Synthesis of gem-Disubstituted Cyclopropanes
Harris, Michael R.,Wisniewska, Hanna M.,Jiao, Wenhua,Wang, Xiaochun,Bradow, James N.
supporting information, p. 2867 - 2871 (2018/05/29)
A diastereoselective, Pd-catalyzed Suzuki-Miyaura coupling reaction of geminal bis(boryl)cyclopropanes has been developed. The reaction offers a highly modular approach to the synthesis of tertiary cyclopropylboronic esters. The resulting boronic esters may be further functionalized to afford a range of gem-disubstituted cyclopropanes, which represent an important structural motif in the pharmaceutical industry. Sequential Suzuki-Miyaura cross-coupling reactions of gem-bis(boryl)cyclopropanes are also reported. The coupling protocols are compatible with a broad range of functionalized aryl and heteroaryl bromides.
Mild Ring-Opening 1,3-Hydroborations of Non-Activated Cyclopropanes
Wang, Di,Xue, Xiao-Song,Houk, Kendall N.,Shi, Zhuangzhi
supporting information, p. 16861 - 16865 (2018/11/27)
The Brown hydroboration reaction, first reported in 1957, is the addition of B?H across an olefin in an anti-Markovnikov fashion. Here, we solved a long-standing problem on mild 1,3-hydroborations of non-activated cyclopropanes. A three-component system including cyclopropanes, boron halides, and hydrosilanes has been developed for borylative ring-opening of cyclopropanes following the anti-Markovnikov rule, under mild reaction conditions. Density functional theory (M06-2X) calculations show that the preferred pathway involves a cationic boron intermediate which is quenched by hydride transfer from the silane.
Alkyl?(Hetero)Aryl Bond Formation via Decarboxylative Cross-Coupling: A Systematic Analysis
Sandfort, Frederik,O'Neill, Matthew J.,Cornella, Josep,Wimmer, Laurin,Baran, Phil S.
supporting information, p. 3319 - 3323 (2017/03/17)
Suzuki, Negishi, and Kumada couplings are some of the most important reactions for the formation of skeletal C?C linkages. Their widespread use to forge bonds between two aromatic rings has enabled every branch of chemical science. The analogous union between alkyl halides and metallated aryl systems has not been as widely employed due to the lack of commercially available halide building blocks. Redox-active esters have recently emerged as useful surrogates for alkyl halides in cross-coupling chemistry. Such esters are easily accessible through reactions between ubiquitous carboxylic acids and coupling agents widely used in amide bond formation. This article features an amalgamation of in-house experience bolstered by approximately 200 systematically designed experiments to accelerate the selection of ideal reaction conditions and activating agents for the cross-coupling of primary, secondary, and tertiary alkyl carboxylic acids with both aryl and heteroaryl organometallic species.
Light-Mediated Reductive Debromination of Unactivated Alkyl and Aryl Bromides
Devery, James J.,Nguyen, John D.,Dai, Chunhui,Stephenson, Corey R. J.
, p. 5962 - 5967 (2016/09/09)
Cleavage of carbon-halogen bonds via either single-electron reduction or atom transfer is a powerful transformation in the construction of complex molecules. In particular, mild, selective hydrodehalogenations provide an excellent follow-up to the application of halogen atoms as directing groups or the utilization of atom transfer radical addition (ATRA) chemistry for the production of hydrocarbons. Here we combine the mechanistic properties of photoredox catalysis and silane-mediated atom transfer chemistry to accomplish the hydrodebromination of carbon-bromide bonds. The resulting method is performed under visible light irradiation in an open vessel and is capable of the efficient reduction of a variety of unactivated alkyl and aryl substrates.
