Highly Stereoselective Synthesis of Bicyclo[n.3.0]alkanes by Titanium Tetrachloride Promoted [3 + 2] Cycloaddition of Allylsilanes and 1-Acetylcycloalkenes
摘要:
AbstractThe titanium tetrachloride promoted reaction of allylsilanes 1 with 1‐acetylcyclohexene is shown to afford the silylbicyclo[4.3.0]nonanes 9 ([3 + 2] cycloaddition products) along with the 1‐acetyl‐2‐allylcyclohexane 4 (Hosomi‐Sakurai product). Here we report that systematic variation of the substituents at the silicon atom of 1 allows suppression of the classical Hosomi‐Sakurai reaction in favor of the [3 + 2] cycloaddition. Cycloaddition of the allylsilanes 1d, 1i, and 1 k with 1‐acetylcycloalkenes 10, containing a 5‐, 6‐, 7‐, 8‐, or 12‐membered ring, gives rise to the corresponding silylbicyclo[n.3.0]alkanes 11 – 13. The cycloaddition of allyltriisopropylsilane (1 k) and 1‐acetyl‐2‐methylcycloalkenes 15 provides silylbicyclo[n.3.0]alkanes 16 with two contiguous quaternary carbon centers. The stereochemistry of the silylbicyclo[n.3.0]alkanes 11 a ‐ c and 14 is unambiguously determined by X‐ray analysis and 13C NMR spectroscopy.
Organocalcium Complex-Catalyzed Selective Redistribution of ArSiH<sub>3</sub> or Ar(alkyl)SiH<sub>2</sub> to Ar<sub>3</sub>SiH or Ar<sub>2</sub>(alkyl)SiH
作者:Tao Li、Karl N. McCabe、Laurent Maron、Xuebing Leng、Yaofeng Chen
DOI:10.1021/acscatal.1c00463
日期:2021.6.4
compounds. Herein, we report the synthesis and structural characterization of two calcium alkyl complexessupported by β-diketiminato-based tetradentate ligands. These two calcium alkyl complexes react with PhSiH3 to generate calcium hydrido complexes, and the stability of the hydrido complexes depends on the supportingligands. One calcium alkyl complex efficiently catalyzes the selective redistribution
Modular Ni(0)/Silane Catalytic System for the Isomerization of Alkenes
作者:Kiana E. Kawamura、Alison Sy-min Chang、Daryl J. Martin、Haley M. Smith、Parker T. Morris、Amanda K. Cook
DOI:10.1021/acs.organomet.2c00010
日期:2022.2.28
versatile catalyticsystem that is effective for the formation of internal alkenes with high yield and selectivity for the E-alkene. The use of silanes as mild activators enables isomerization of substrates with a variety of functional groups, including acid-labile groups. The broad substrate scope, enabled by catalyst design, makes this catalyticsystem a strong candidate for use in tandem catalytic applications
The mechanism of oxidative addition of Pd(0) to Si–H bonds: electronic effects, reaction mechanism, and hydrosilylation
作者:Michael R. Hurst、Lev N. Zakharov、Amanda K. Cook
DOI:10.1039/d1sc04419b
日期:——
temperature-dependent intramolecular H/Si ligand exchange on the NMR timescale, allowing determination of the energetic barrier to reversible oxidativeaddition. Taken together, these results give unique insight into the individual steps of oxidativeaddition and suggest the initial formation of a σ-complex intermediate to be rate-limiting. The insight gained from these mechanistic studies was applied