sequential reactions using silyl group-substituted titanium carbene complexes was studied. Dienylsilanes were obtained by the olefination of carbonyl compounds with γ-silylvinylcarbene complexes. Cyclopropanation of 1-alkenes with the vinylcarbene complexes produced (E)-(β-silylvinyl)cyclopropanes with high stereoselectivity. The reaction of β-(trialkylsilyl)carbene complexes with zinc alkoxides of homopropargyl
Bifunctional Polyene Cyclizations: Synthetic Studies on Pimarane Natural Products
作者:Julian M. Feilner、Immanuel Plangger、Klaus Wurst、Thomas Magauer
DOI:10.1002/chem.202101926
日期:2021.8.25
Polyenecyclizations generate molecular complexity from a linear polyene in a single step. While methods to initiate these cyclizations have been continuously expanded and improved over the years, the majority of polyene substrates are still limited to simple alkyl-substituted alkenes. In this study, we took advantage of the unique reactivity of higher-functionalized bifunctional alkenes. The realization
Ru-Catalyzed Migratory Geminal Semihydrogenation of Internal Alkynes to Terminal Olefins
作者:Lijuan Song、Qiang Feng、Yong Wang、Shengtao Ding、Yun-Dong Wu、Xinhao Zhang、Lung Wa Chung、Jianwei Sun
DOI:10.1021/jacs.9b09658
日期:2019.10.30
the gem-H2 Ru-carbene might be the key intermediate in both gem- and trans-addition reactions, rather than the Ru-vinylidene intermediate. The DFT results were further supported by carefully designed control experiments. This uncommon gem-addition combined with 1,2-silyl migration in the metal-carbene intermediate should open up a new synthetic avenue for alkyne transformations.
Stereospecific Synthesis of Cyclobutylboronates through Copper(I)-Catalyzed Reaction of Homoallylic Sulfonates and a Diboron Derivative
作者:Hajime Ito、Takashi Toyoda、Masaya Sawamura
DOI:10.1021/ja101793a
日期:2010.5.5
A copper(I)-catalyzed stereospecific reaction for the preparation of cis- and trans-1-silyl-2-borylcyclobutanes as well as 1-phenyl-2-borylcyclobutanes is reported. (Z)- and (E)-Homoallylic methanesulfonates were converted to the corresponding trans- and cis-cyclobutane derivatives, respectively, in the presence of a CuCl/dppp catalyst, bis(pinacolato)diboron, and K(O-t-Bu)/THF. Stereospecific derivatizations
New Catalytic Asymmetric Formation of Oxygen Heterocycles Bearing Nucleoside Bases at the Anomeric Carbon
作者:Barry M. Trost、Shiyan Xu、Ehesan U. Sharif
DOI:10.1021/jacs.9b06050
日期:2019.7.3
formed glyosidic bond. Herein, we report an asymmetric Pd-catalyzed synthesis of nucleoside analogs enabled by the development of a series of chiral ligands. A variety of 5-substituted pyrimidine nucleobases, ranging from 5- to 12-membered ring nucleoside analogs are generated in good yield (68% to 96%), diastereo- (> 20:1), and enantioselectivity (85% ee to 99.5% ee). These nucleoside analogs bearing an