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A Specific Route to Enantiomerically Pure Asymmetric (η 6 ‐Arene)(η 4 ‐1,5‐cyclooctadiene)Ru(0) Complexes
Author(s) -
Heinemann Frank,
Klodwig Ens,
Knoch Falk,
Wündisch Marion,
Zenneck Ulrich
Publication year - 1997
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19971300121
Subject(s) - chemistry , diastereomer , electrophile , naphthalene , bromine , alkyl , medicinal chemistry , cyclooctadiene , counterion , catalysis , organic chemistry , ion
Chiral or achiral (arene)(COD)Ru complexes can be made by replacing the η 6 ‐ligands of (η 4 ‐1,5‐COD)(η 6 ‐1,3,5‐cyclooctatriene)Ru ( 1 ) or (η 4 ‐1,5‐COD)(η 6 ‐naphthalene)Ru ( 2 ) by a suitable arene. This well known reaction has been extended to mono‐ and dibromoarenes and we report a novel route to substituted (arene)(COD)Ru species, utilizing (bromoarene)‐(COD)Ru as starting materials. These facilitate a rapid bromine‐lithium exchange reaction with n BuLi at low temperatures and the lithiated species react readily with alkyl chloroformates as electrophiles. By using chiral electrophiles [alkyl = (‐)‐menthyl] enantiomerically pure or diastereomeric complexes containing CO 2 R * groups are formed, depending on the symmetry of the original complex. A diastereomeric 1:1 mixture was separated by recrystallization. All (arene)‐(COD)Ru complexes tested so far are useful as catalysts for the hydrogenation of simple alkenes at room temperature.