Enantioselective oxidative-coupling of polycyclic phenols such as 2-anthracenol, 9-or 3phenanthrol, and 5-chrysenol was established by using vanadium(V/IV) catalysis under air or O2 as a co-oxidant. In the vanadium catalyzed reaction, the corresponding coupling products were obtained in good to excellent yields with up to 93% enantiomeric excess.
The oft-claimed good water solubility of the food color norbixin (3) could not be confirmed. In contrast, the potassium salt 5 of norbixin formed suitable dispersions. The surface and aggregation properties of salt 5 were investigated and compared with other naturally occurring and synthetic hydrophilic carotenoids (Table).
The reaction of the μ(3)-oxido-centred trinuclear isobutyrate cluster [Fe(3)O(O(2)CCHMe(2))(6)(H(2)O)(3)](+) with an excess of phenol (PhOH) in chloroform produces a novel octanuclear Fe(III) cluster, cyclo-tetra-μ(2)-hydroxido-dodeca-μ(2)-isobutyrato-κ(24)O:O'-octa-μ(2)-phenolato-κ(16)O:O'-octairon(III) phenol hexasolvate monohydrate, [Fe(8)(C(4)H(7)O(2))(12)(C(6)H(5)O)(8)(OH)(4)]·6C(6)H(5)OH·H(2)O. The neutral cluster is located about a centre of inversion and consists of a planar ring of eight Fe(III) centres with two types of bridges between adjacent Fe atoms: each Fe atom is bridged to one of its neighbours by a μ-hydroxide and two 1,3-bridging carboxylates, or by two phenolate and one 1,3-bridging isobutyrate ligand. The cavity within the {Fe(8)} wheel is occupied by a disordered water molecule. Intermolecular O-H···O hydrogen bonds and C-H···π interactions connect the clusters and the phenol solvent molecules to form a three-dimensional network.
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