20758-60-5Relevant academic research and scientific papers
Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
Liu, En-Chih,Topczewski, Joseph J.
supporting information, p. 5308 - 5313 (2021/05/04)
The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
Nickel-catalyzed Heck reaction of cycloalkenes using aryl sulfonates and pivalates
Zhou, Jianrong Steve,Huang, Xiaolei,Teng, Shenghan,Chi, Yonggui Robin
supporting information, p. 3933 - 3936 (2021/04/26)
Nickel-catalyzed Heck reaction of cycloalkenes delivers unusual conjugated arylated isomers. Nickel(0) catalysts ligated by chelating dialkylphosphines effectively activate not only aryl triflates as electrophiles, but also less reactive aryl mesylates, t
Regiodivergent DH or HD Addition to Alkenes: Deuterohydrogenation versus Hydrodeuterogenation
Hilt, Gerhard,Li, Luomo
supporting information, (2020/03/03)
The regioselective and regiodivergent addition of H-D to a variety of 1,1-diarylalkenes was realized utilizing selectively deuterated dihydroaromatic compounds, which were generated by cobalt catalysis. The reaction was initiated by catalytic amounts of B
Grubbs Metathesis Enabled by a Light-Driven gem-Hydrogenation of Internal Alkynes
Biberger, Tobias,Fürstner, Alois,Zachmann, Raphael J.
, p. 18423 - 18429 (2020/08/25)
[(NHC)(cymene)RuCl2] (NHC=N-heterocyclic carbene) complexes instigate a light-driven gem-hydrogenation of internal alkynes with concomitant formation of discrete Grubbs-type ruthenium carbene species. This unorthodox reactivity mode is harnessed in the form of a “hydrogenative metathesis” reaction, which converts an enyne substrate into a cyclic alkene. The intervention of ruthenium carbenes formed in the actual gem-hydrogenation step was proven by the isolation and crystallographic characterization of a rather unusual representative of this series carrying an unconfined alkyl group on a disubstituted carbene center.
Electro-Olefination—A Catalyst Free Stereoconvergent Strategy for the Functionalization of Alkenes
Baumann, Andreas N.,Dechent, Jonas,Didier, Dorian,Jagau, Thomas C.,Müller, Nicolas,Music, Arif
supporting information, (2020/07/04)
Conventional methods carrying out C(sp2)?C(sp2) bond formations are typically mediated by transition-metal-based catalysts. Herein, we conceptualize a complementary avenue to access such bonds by exploiting the potential of electrochemistry in combination with organoboron chemistry. We demonstrate a transition metal catalyst-free electrocoupling between (hetero)aryls and alkenes through readily available alkenyl-tri(hetero)aryl borate salts (ATBs) in a stereoconvergent fashion. This unprecedented transformation was investigated theoretically and experimentally and led to a library of functionalized alkenes. The concept was then carried further and applied to the synthesis of the natural product pinosylvin and the derivatization of the steroidal dehydroepiandrosterone (DHEA) scaffold.
Pd-catalyzed cross-coupling of highly sterically congested enol carbamates with grignard reagents via c-o bond activation
Chen, Zicong,So, Chau Ming
, p. 3879 - 3883 (2020/06/08)
The palladium-catalyzed cross-coupling reaction of enol carbamates to construct highly sterically congested alkenyl compounds is presented for the first time. This protocol demonstrates the potential of using thermally stable and highly atom-economic enol electrophiles as building blocks in bulky alkene synthesis. This reaction accommodates a broad substrate scope with excellent Z/E isomer ratios, which also provides a new synthetic pathway for accessing Tamoxifen.
Lewis Acid Catalyzed Transfer Hydromethallylation for the Construction of Quaternary Carbon Centers
Walker, Johannes C. L.,Oestreich, Martin
supporting information, p. 15386 - 15389 (2019/10/28)
The design and gram-scale synthesis of a cyclohexa-1,4-diene-based surrogate of isobutene gas is reported. Using the highly electron-deficient Lewis acid B(C6F5)3, application of this surrogate in the hydromethallylation of electron-rich styrene derivatives provided sterically congested quaternary carbon centers. The reaction proceeds by C(sp3)?C(sp3) bond formation at a tertiary carbenium ion that is generated by alkene protonation. The possibility of two concurrent mechanisms is proposed on the basis of mechanistic experiments using a deuterated surrogate.
Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
Ganiu, Moshood O.,Cleveland, Alexander H.,Paul, Jarrod L.,Kartika, Rendy
, p. 5611 - 5615 (2019/08/01)
The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the Zaitzev products is observed when the reaction is carried out in dichloroethane at reflux.
Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
Liu, En-Chih,Topczewski, Joseph J.
supporting information, p. 5135 - 5138 (2019/03/29)
The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would
Cyclopentene Annulations of Alkene Radical Cations with Vinyl Diazo Species Using Photocatalysis
Sarabia, Francisco J.,Li, Qiankun,Ferreira, Eric M.
supporting information, p. 11015 - 11019 (2018/07/30)
A direct (3+2) cycloaddition between alkenes and vinyl diazo reagents using either Cr or Ru photocatalysis is described. The intermediacy of a radical cation species enables a nucleophilic interception by vinyl diazo compounds, a departure from their trad
