Stereodefined Substituted Cyclopropyl Zinc Reagents from Gem-Bismetallics
摘要:
1,1- or n,n-Bismetallic reagents bearing a methoxymethyl ether in the gamma position undergo cyclization at room temperature to give monometalated, diastereoselectively substituted cyclopropanes, The nature of the substituents is crucial for this diastereoselection, a pi-chelation between one metal and a properly located unsaturation, as well as 1,2-strain, are proposed to explain the steric outcome of these reactions.
We describe the synthesis and biological evaluation of (+)-neopeltolide analogues with structural modifications in the oxazole-containing side chain. Evaluation of the antiproliferative activity of newly synthesized analogues against A549 human lung adenocarcinoma cells and PANC-1 human pancreatic carcinoma cells have shown that the C19–C20 and C26–C27 double bonds within the oxazole-containing side
Copper(I)-Catalyzed Coupling of Terminal Acetylenes with Aryl or Vinyl Halides
作者:D. Venkataraman、Pranorm Saejueng、Craig G. Bates
DOI:10.1055/s-2005-869893
日期:——
Synthetic protocols using copper(I) catalysts for the for- mation of diaryl acetylenes, 1,3-enynes, benzofurans and indoles are described. The acetylenic moiety is an important unit found in many compounds that are of pharmaceutical, biological and ma- terial interests. 1 Aryl acetylenes are constituent units in important conjugated polymers. 1c 1,3-Enynes are found in many biologically and pharmaceutically
Ligand Effects on the Pd-Catalyzed Cross-Coupling Reaction of 3-Iodoalk-2-enoates with Propargyl/1,2-Allenylic Metallic Species: An Efficient Regiodivergent Synthesis of 2,4,5-Trienoates
作者:Jinbo Zhao、Yihua Yu、Shengming Ma
DOI:10.1002/chem.200901287
日期:2010.1.4
makes a big difference: The 1,3‐lithiumshift of propargyl/1,2‐allenyl lithium has been tuned and applied in a subsequenttransmetalation and Pd‐catalyzed Negishi couplingreaction with 3‐iodoalk‐2‐enoates to give a highly regioselective and regiodivergent synthesis of 2,4,5‐trienoates. It was discovered that ligands play a very important role in the cross‐couplingreactions with respect to both regioselectivity