Correlation between functionality preference of Ru carbenes and exo/endo product selectivity for clarifying the mechanism of ring-closing enyne metathesis.
Functionality preferences of metathesis Ru carbenes to various alkenes and alkynes with electronic and steric diversity were determined by using time-dependent fluorescence quenching. The functionality preferences depend not only on the properties of multiple bonds but also on the ligands on Ru. There was a good correlation between functionality preference and the metathesis reaction outcome. The correlation between functionality preference and exo/endo product ratio offers a solution to resolve the mechanistic issue related with alkene- vs alkyne-initiated pathway in ring-closing enyne metathesis. The correlation indicates the preference is likely to dictate the reaction pathway and eventually the outcome of the reaction. The Ru catalyst favoring alkyne over alkene provides more endo product, indicating that the reaction mainly initiates at the alkyne. By changing the substitution pattern, the preference can be reversed to give an exclusive exo product.
Department of Chemistry, College of Natural Sciences, Chungnam National University, Daejeon 305-764, Korea.
Ok Suk
OS
Lee
Kyung Hwan
KH
Kim
Jinwoo
J
Kim
Kuktae
K
Kwon
Taedong
T
Ok
Hyotcherl
H
Ihee
Hee-Yoon
HY
Lee
Jeong-Hun
JH
Sohn
D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D005453:Fluorescence; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013997:Time Factors
D000475:Alkenes; D000480:Alkynes; D008024:Ligands; D009942:Organometallic Compounds; C030011:carbene; D012428:Ruthenium; D008697:Methane