Reversible Formation of a Planar Chiral Ferrocenylboroxine and Its Supramolecular Structure

Thilagar, Pakkirisamy and Chen, Jiawei and Lalancette, Roger A and Jaekle, Frieder (2011) Reversible Formation of a Planar Chiral Ferrocenylboroxine and Its Supramolecular Structure. In: Organometallics, 30 (24). pp. 6734-6741.

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Abstract

The boronic acid (pS)-1,2-NpFcB(OH)(2) (1) was obtained by treatment of the lithiated species (pS)-1,2-NpFcLi with B(O(i)Pr)(3), followed by acidic workup; subsequent dehydration gave the enantiomerically pure boroxine [(pS)-1,2-NpFcBO](3) (2) in 49% isolated yield. Multinuclear and 2D NMR spectroscopies, single-crystal X-ray diffraction, and elemental analysis served to confirm the structure of 2. In the solid-state structure, all three of the naphthyl groups point in one direction and all of the ferrocenyl moieties are placed on the opposite face of the boroxine ring, which is also the preferred conformation in solution according to a (1)H, (1)H-NOESY experiment. Cyclic voltammetry revealed three separate reversible oxidation events, which suggests significant communication between the ferrocenyl moieties. These redox processes experience a cathodic shift upon addition of 4-dimethylaminopyridine (DMAP) as a Lewis base. The six-membered ring is opened upon treatment with hot CHCl(3)/MeOH to form the methoxy species (pS)-1,2-NpFcB(OH)(OMe) (3), which can be converted back to the cycle 2 by dissolution in wet CHCl(3), followed by column chromatography on silica gel.

Item Type:	Journal Article
Publication:	Organometallics
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	27 Jan 2012 06:28
Last Modified:	27 Jan 2012 06:28
URI:	http://eprints.iisc.ac.in/id/eprint/43149

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