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Ruthenium(II)‐Catalyzed Oppenauer‐Type Oxidation of Secondary Alcohols
Author(s) -
Almeida Maria L. S.,
Beller Marion,
Wang GuoZ.,
Bäckvall JanE.
Publication year - 1996
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.19960021210
Subject(s) - chemistry , ruthenium , catalysis , isomerization , allylic rearrangement , hydride , dehydrogenation , acetone , kinetic isotope effect , medicinal chemistry , rate determining step , photochemistry , alcohol oxidation , organic chemistry , hydrogen , deuterium , physics , quantum mechanics
Highly efficient ruthenium‐catalyzed Oppenauer‐type oxidations of secondary alcohols to ketones have been developed. The catalytic system consists of [(PPh 3 ) 3 RuCl 2 ] ( 1 ) and K 2 CO 3 or [(C 4 Ph 4 COHOCC 4 Ph 4 )(μ‐H)(CO) 4 Ru 2 ] ( 2 ) in refluxing acetone. The catalytic reaction is of high efficiency and permits a catalyst: substrate ratio of 1:1000 at 56 °C. In some cases the initial turnover rate exceeds 1500 h ‐1 . The reaction was found to be general and compatible with double bonds and oxidation‐sensitive aromatics. With some allylic alcohols, isomerization to saturated ketones took place. The reaction proceeds by ruthenium‐catalyzed dehydrogenation of the alcohol and subsequent hydrogen transfer to acetone. No primary kinetic isotope effect was observed for the catalytic reaction when α‐deuterated 1‐phenylethanol was employed as substrate ( k H / k D =1.1); this shows that β‐hydride elimination from a ruthenium alkoxide intermediate is not the rate‐limiting step.