Issue 12, 2010

Basicity and bulkiness effects of 1,8-diaminonaphthalene, 8-aminoquinoline and their alkylated derivatives on the different efficiencies of η5-C5H5 and η5-C5Me5 ruthenium precatalysts in allylic etherification reactions

Abstract

The different behaviours of Ru(η5-C5H5) and Ru(η5-C5Me5) precatalysts, [Ru(η5-C5R5)(NCMe)(N,N)]PF6 (R = H, Me), in the allylic etherification reaction of cinnamyl chloride using the phenoxide anion as a nucleophile was considered. The N,N ligands are the commercial products 1,8-diaminonaphthalene and 8-aminoquinoline, and their derivatives obtained by alkylation of the amino nitrogen atoms: alkyl substituents that are also bulky chiral C2-symmetric frameworks allow modulation of the basicity and steric demand of the ligands. Some of the precatalysts, [Ru(η5-C5R5)(NCMe)(N,N)]PF6 (R = H, Me), were also synthesized and characterized. The cinnamyl phenyl ether isomers were obtained with very high B/L regioselectivity values, either with Ru(η5-C5H5) or Ru(η5-C5Me5) precatalysts. The highest B/L regioselectivity values achieved with Ru(η5-C5Me5) precatalysts were found with the N,N ligand 1,8-diaminonaphthalene and its derivatives; with Ru(η5-C5H5) precatalysts best B/L values were obtained with ligands derived from 8-aminoquinoline. A correlation between the B/L regioselectivity, and the σ-donor power and bulkiness of the substituents at the nitrogen atoms of the N,N coordinated ligand was established, but the Ru(η5-C5H5) or Ru(η5-C5Me5) precatalysts followed an opposite trend. It was also found that the low ee values did not depend on the diastereomeric composition of the chiral-at-metal precatalyst [Ru(η5-C5R5)(NCMe)(N,N)]PF6.

Graphical abstract: Basicity and bulkiness effects of 1,8-diaminonaphthalene, 8-aminoquinoline and their alkylated derivatives on the different efficiencies of η5-C5H5 and η5-C5Me5 ruthenium precatalysts in allylic etherification reactions

Supplementary files

Article information

Article type
Paper
Submitted
02 May 2010
Accepted
25 Jun 2010
First published
31 Aug 2010

New J. Chem., 2010,34, 2853-2860

Basicity and bulkiness effects of 1,8-diaminonaphthalene, 8-aminoquinoline and their alkylated derivatives on the different efficiencies of η5-C5H5 and η5-C5Me5 ruthenium precatalysts in allylic etherification reactions

G. Brancatelli, D. Drommi, G. Feminò, M. Saporita, G. Bottari and F. Faraone, New J. Chem., 2010, 34, 2853 DOI: 10.1039/C0NJ00338G

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