Regioselective Cyclometalation of Planar Chiral Pyridine and Oxazoline Derivatives: peri- versus ortho-C鈥揌 Functionalization

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• 作者：Audrey Mercier ; Simon Wagschal ; Laure Gu茅n茅e ; C茅line Besnard ; E. Peter K眉ndig
• 刊名：Organometallics
• 出版年：2013
• 出版时间：July 22, 2013
• 年：2013
• 卷：32
• 期：14
• 页码：3932-3942
• 全文大小：544K
• 年卷期：v.32,no.14(July 22, 2013)
• ISSN：1520-6041

文摘

The cyclopalladation of highly enantioenriched cyclopentadienyl(indenyl)ruthenium complexes featuring pyridine or oxazoline functionalities as directing groups is detailed. Two competitive metalation sites inherent to the fused ring system were selectively activated after appropriate tuning of the reaction conditions, enabling the access to both six (peri)- and five-membered (ortho) membered chelates. A peri 鈫?ortho isomerization was identified in the pyridine-based system, unveiling a kinetic preference for the peri-position and thermodynamic control for the ortho-cyclopalladation. In marked contrast, oxazoline derivatives incorporating a stereogenic center at C4 proved reluctant to form ortho-isomers and were exclusively converted into the corresponding peri-palladacyles at low temperatures.