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Microwave‐Assisted Transfer Hydrogenation of Ketones by Ru(xantphos) Arene Complexes
Author(s) -
Marimuthu Thashree,
Friedrich Holger B.
Publication year - 2012
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201200306
Subject(s) - xantphos , acetophenone , chemistry , catalysis , transfer hydrogenation , benzophenone , medicinal chemistry , microwave irradiation , yield (engineering) , organometallic chemistry , organic chemistry , ruthenium , palladium , materials science , metallurgy
A Ru‐catalyzed hydrogen transfer from 2‐propanol to acetophenone in the presence of the strong base KO t Bu afforded 1‐phenyl alcohol in >99 % yield within 5 min under microwave irradiation; no reaction occurred in the absence of the base. A series of catalysts was then prepared in situ from [RuCl 2 ‐η 6 ‐ p ‐cymene] 2 and xantphos family ligands, which were characterized by having natural bite angles ranging from 102.2 to 137.9°. The Ru(xantphos)arene catalyst was used for various substrates to give yields and turnover frequencies between 48 and 99 % and between ≥1431 and 2982 h −1 , respectively, for acetophenone derivatives and >99 % and ≥2982 h −1 for sterically bulky ketones (benzophenone, 9 H ‐fluoren‐9‐one, and α‐tetralone).