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Acceleration Effect of an Allylic Hydroxy Group on Ring‐Closing Enyne Metathesis of Terminal Alkynes: Scope, Application, and Mechanistic Insights
Author(s) -
Imahori Tatsushi,
Ojima Hidetomo,
Yoshimura Yuichi,
Takahata Hiroki
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801439
Subject(s) - allylic rearrangement , enyne metathesis , enyne , chemistry , salt metathesis reaction , metathesis , ethylene , ring (chemistry) , stereochemistry , medicinal chemistry , catalysis , organic chemistry , polymer , polymerization
An interesting acceleration effect of an allylic hydroxy group on ring‐closing enyne metathesis has been found. Ring‐closing enyne metathesis of terminal alkynes possessing an allylic hydroxy group proceeded smoothly without the ethylene atmosphere generally necessary to promote the reaction. The synthesis of (+)‐isofagomine with the aid of this efficient reaction has been demonstrated. Mechanistic studies of the acceleration effect were also carried out. Results of NMR studies suggested that the reaction proceeded via an “ene‐then‐yne” pathway. Kinetic studies indicated switching of the rate‐determining step as a consequence of the presence of an allylic hydroxy group. These results suggest acceleration of the reentry step of Ru‐carbene species by the allylic hydroxy group.