Synthesis of benzofuran derivatives through the coupling of conjugated dienynes with Fischer carbene complexes
作者:James W Herndon、Yi Zhang、Haixia Wang、Ke Wang
DOI:10.1016/s0040-4039(00)01574-4
日期:2000.11
The reaction of Fischer carbene complexes with conjugated dienylacetylene derivatives followed by treatment with iodine leads to benzofuran derivatives in good-to-excellent yields. Equivalent products can be obtained from coupling of conjugated enediynes with Fischer carbene complexes in the presence of hydrogen atom donors.
Coupling of Fischer carbene complexes with conjugated enediynes featuring radical traps: Novel structure and reactivity features of chromium complexed arene diradical species
作者:Yi Zhang、Tareq Irshaidat、Haixia Wang、Kris V. Waynant、Haobin Wang、James W. Herndon
DOI:10.1016/j.jorganchem.2008.08.003
日期:2008.10
The reaction of Fischer carbene complexes with conjugated enediynes that feature a pendant alkene group has been examined. The reaction proceeds through carbene-alkyne coupling to generate an enyne-ketene intermediate. This intermediate then undergoes Moore cyclization to generate a chromium complexed arene diradical, which then undergoes cyclization with the pendant alkene group. The radical cyclization prefers the 6-endo mode unless radical-stabilizing groups are present to favor the 5-exo mode. The intermediate diradical species were evaluated computationally in both the singlet and triplet configurations. Arene triplet diradicals feature minimal spin density at oxygen and delocalization to chromium. The 6-endo cyclization product was kinetically and thermodynamically favored. (C) 2008 Elsevier B.V. All rights reserved.
Gold-Catalyzed Stereoselective Synthesis of Di- or Trisubstituted Olefins Possessing a 1,4-Diene Framework via Intramolecular Allylation of Alkynes
The cationic gold(I)-catalyzed reaction of 1-alkynyl-2-allylsilylbenzenes with water results in intramolecular allylation of the alkynes via 7-exo-dig cyclization to give 1,4-dienes in good yield with excellent stereoselectivities.