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Ruthenium Complexes Bearing Bulky Pentasubstituted Cyclopentadienyl Ligands and Evaluation of [Ru(η 5 ‐C 5 Me 4 R)(MeCN) 3 ][PF 6 ] Precatalysts in Nucleophilic Allylic Substitution Reactions
Author(s) -
Zhang HuiJun,
Demerseman Bernard,
Xi Zhenfeng,
Bruneau Christian
Publication year - 2008
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200800295
Subject(s) - chemistry , allylic rearrangement , cyclopentadienyl complex , ruthenium , regioselectivity , medicinal chemistry , nucleophile , aryl , catalysis , ether , stereochemistry , ring (chemistry) , nucleophilic substitution , ligand (biochemistry) , organic chemistry , alkyl , biochemistry , receptor
[Ru(η 5 ‐C 5 Me 4 R)(MeCN) 3 ][PF 6 ] (R = CH 2 t Bu, i Pr, t Bu, and CF 3 ; 2 – 5 ) complexes were synthesized in two steps starting from the appropriate cyclopentadienes and RuCl 3 · 3H 2 O. The fully substituted ruthenocenes [Ru(C 5 Me 5 )(C 5 Me 4 R*)], [Ru(C 5 Me 5 )(C 5 n Pr 4 R*)] {R* = (1 R,5S )‐6,6‐dimethylbicyclo[3.1.1]hept‐2‐en‐2‐yl} and [Ru(C 5 Me 5 )(C 5 n Pr 5 )] were obtained by treating [Ru(C 5 Me 5 )Cl] 4 with the corresponding cyclopentadienyllithium salts. Complexes 2 – 5 were evaluated as catalyst precursors for nucleophilic allylic substitution reactions, and the results were compared to those obtained with the [Ru(C 5 Me 5 )(MeCN) 3 ][PF 6 ] ( 1 ) precatalyst. The etherification of p ‐methoxyphenol with the typical aliphatic chlorohexene allylic substrate shows that the introduction of the bulky tert ‐butyl and trifluoromethyl groups into the tetramethylcyclopentadienyl ring results in a valuable enhancement in regioselectivity in favour of the branched allyl aryl ether.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)