Symbioramide [ (2S,2'R,3R,3'E)-N-(2'-hydroxy-3'-octadece-2-octadecen-1-01 (4) by employing the Sharpless asymmetric noyl)dihydrosphingosine, 11 was synthesized from D-erythro-epoxidation. The (2S,2'S,3R,3'E)-isomer 28 of 1 was also syndihydrosphingosine (19) and (R,E)-2'-tert-butyldimethylsilyl-thesized to further confirm the structure of 1. oxy-3'-octadecenoic acid (14), which was prepared from (E)-
Newly devised 13-15-membered macrocyclic tetraamine (N4) ligands attached with a phenolic pendant (10,11,13, and 15) have been synthesized to determine the influence of the phenol on the cation-enclosure properties of the macrocyclic N4 and, conversely, the influence of the proximate cations encompassed in N4 macrocycles on the chemical behavior of the phenolate pendant. The synthesis involves a novel annelation reaction between coumarin and suitable tetraamines. The favorable location of phenol in the periphery of the macrocycle has been confirmed by the X-ray crystal structure of the phenol-pendant 14-membered N4 (cyclam) lib. Dissociation of the phenolic protons is facilitated by incorporation of metal ions into the macrocycle, and the resulting phenolate ion atop stabilizes otherwise unstable complexes. The crystal structures of lib and its Cu11 complex 17a have been determined. The crystals of lib (C16H28N40) are monoclinic, space group P2¡/a, with four molecules in the unit cell of dimensions a = 15.335 (8) A, b = 8.535 (5) A, c = 13.331 (7) A, and ß = 105.17 (5)°. Crystals of 17a(C104)-H20 (C16H27N40CuC104-H20) are also monoclinic, space group P2¡/n, with four molecules in the unit cell of dimensions a = 30.943 (20) A, b = 8.188 (4) A, c = 7.936 (4) A, and ß = 95.89 (5)°. The structures were solved by the direct method for lib and the heavy-atom method for 17a and refined by block-diagonal least-squares calculations: for lib, R = 0.061 for 2635 independent reflections, and for 17a, R = 0.066 for 3703 independent reflections. The five-coordinate, square-pyramidal geometry around copper is illustrated with the phenolate oxygen at nearly the apex of the pyramid. The pH-metric and polarographic titration of Cun-llb revealed a complexation constant ([CuH_1L+]/[CuII][H_lL~]) of 1.0 X 1032 M"1 (H_,L is the phenolate species) and stability enhancement of ~10* 12 by the phenolate coordination. Its strong a donation contributes to stabilization of higher oxidation states of metal ions. Saturated polyamine macrocycles possess cavities capable of providing a favorable environment for the reception of guest cation and anion species.1 The strength of the ion binding is determined
The cis-macrocyclic configuration in the phenol-pendant-[l 31aneN4 [I 1-(2'-hydroxyphenyl)-I ,4,7,1 O-tetra-azacyclotridecane] complex with Nil1 rapidly rearranges to a 'square planar' form upon oxidation to Ni l 11 at ca.
With the aim of applying mast cell-stabilizing agents as antiulcer agents, N-(1H-tetrazol-5-yl)-2-anilino-5-pyrimidinecarboxamides were synthesized, and initially evaluated pharmacologically for activity in the rat passive cutaneous anaphylaxis test by oral administration. The most active compound 6 was proved to inhibit potently the release of histamine from passively sensitized rat peritoneal mast cells in vitro. When compared with other mast cell-stabilizing agents and an antiulcer agent, compound 6 was found to show excellent gastric mucosal protection and gastric antisecretion activities. Furthermore, compound 6 revealed good activity against acidified aspirin ulcer in rats and water-immersion stress ulcer in rats.
In crystal structure of NiII-phenol-pendent[13]aneN4 complex 3 the pendent phenolate coordinates to high-spin NiII in a folded[13]aneN4: in aqueous solution, the equilibrium of phenol\ightleftarrowsphenolate directly determines low-spin, square-planar or high-spin, folded macrocyclic structure.
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