Diverse C–C Bond-Forming Reactions of Bis(carbene)platinum(II) Complexes
作者:Rachel C. Klet、Jay A. Labinger、John E. Bercaw
DOI:10.1021/om300733h
日期:2012.9.24
The platinum(0) complex Pt(PPh3)4 catalyzes coupling of the carbene ligands of (CO)5CrC(OMe)(p-MeOC6H4)} (1). The stable bis(carbene)platinum(II) complexes Cl2PtC(OMe)(Me)}2 (3), Br2PtC(OMe)(Me)}2 (4), and Cl2PtC(OiPr)(Me)}2 (5) can be induced to undergo C–C coupling reactions by several means. Reduction of 3–5 to platinum(0) with cobaltocene results in formation of internal olefins, (E/Z)-2,3-dimethoxybut-2-ene
Fischer Carbene Pentannulation with Alkynes Having Adjacent Carbonate or Acyloxy Groups: Synthesis of 3-Substituted 1-Indanones
作者:Rodney A. Fernandes、Sachin P. Gholap、Vijay P. Chavan、Akeel S. Saiyed、Shubhankar Bhattacharyya
DOI:10.1021/acs.orglett.0c00901
日期:2020.5.1
Various aryl Fischercarbenes reacted with alkynes having adjacent acyloxy or carbonate groups to regioselectively deliver 3-substituted 1-indanones. The acyloxy or carbonate group probably coordinates with the Cr metal to give a tetra-coordinated chromium complex forming a six-membered ring that retards CO insertion for ketene formation, which is required for benzannulation. Alternatively, the ortho
sequential treatment of an acetylide with a Fischercarbenecomplex and an alkene/diene yields alkynylcyclopropanes with a wide substitution range. The intramolecular process provides 1‐alkynylbicyclo[3.1.0]cyclohexanes by starting from 1,6‐enynes. A non‐heteroatom‐stabilized metal alkynylcarbene is responsible for the selectivetransfer of the propargylene unit.
Enantioselective Multicomponent Synthesis of Fused 6-5 Bicyclic 2-Butenolides by a Cascade Heterobicyclisation Process
作者:Marcos G. Suero、Raquel De la Campa、Laura Torre-Fernández、Santiago García-Granda、Josefa Flórez
DOI:10.1002/chem.201102288
日期:2012.6.4
heterobicyclisation products is the result of the regioselective integration of the Grignardreagent as a propargyl fragment followed by a cascade CO/alkyne/CO insertion, ketene trapping and elimination sequence. By using lithium enolates of chiral N‐acetyl‐2‐oxazolidinones and the corresponding propargylic organocerium reagents, both enantiomers of these bicyclic heterocycles were efficiently prepared with
patterns: Gold(I) catalyzes the conversion of cyclopentenes (1/1′) into cyclohexadienes (2/3). This profound skeleton rearrangement comprises ring expansion and a [1,2]‐alkynyl shift, and is thought to be initiated by the cleavage of the bridging CC bond. The proposed allyl–gold cation intermediate is trapped with alcohols to provide bicyclo[3.2.1]octadiene and tricyclo[3.2.1.02,7]octane derivatives.