Exploiting the Reversibility of Olefin Metathesis. Syntheses of Macrocyclic Trisubstituted Alkenes and (<i>R,R</i>)-(−)-Pyrenophorin
作者:Alois Fürstner、Oliver R. Thiel、Lutz Ackermann
DOI:10.1021/ol0069554
日期:2001.2.1
trisubstituted cycloalkene 7 by RCM of diene 5 proceeds via the acyclic dimer 6, thus demonstrating the ready reversibility of olefin metathesis if catalyzed by "second generation" ruthenium carbene complexes such as 2-4. When applied to acrylate 11, these catalysts trigger a cyclooligomerization process that evolves with time and serves as key step en route to the lactide antibiotic (-)-pyrenophorin 8.
Formation of Macrocycles <i>via</i> Ring-Closing Olefin Metathesis
作者:Choon Woo Lee、Robert H. Grubbs
DOI:10.1021/jo0158480
日期:2001.10.1
The enhanced metathesis activity of 1,3-dimesityl-4,5-dihydroimidazole-2-ylidene ruthenium carbene catalyst 3 significantly increases the feasibility of synthesizing macrocyclic compounds. Catalyst 3 exhibits sufficient activity in RCM to dimerize alpha,beta-unsaturated ester substrates and afford the corresponding head-to-tail (E,E)-dimeric (and trimeric) macrocycles. The dimerization appears to be