Yasuo Morita

Studies on the binding mechanism of fluoroquinolones to melanin

Abstract In order to elucidate the binding mechanism of melanin and fluoroquinolones (ofloxacin, norfloxacin, ciprofloxacin, lomefloxacin, levofloxacin), we investigated the interaction of fluoroquinolones with compounds such as l-β-(3,4-dihydroxyphenyl) alanine (l-DOPA), l-tyrosine, 5-hydroxy-l-tryptophan, l-tryptophan, and l-phenylalanine, which possess the kind of functional groups that melanin does and are closely related to melanin. The recovery of drugs from the melanin-drug complexes by metal ions of Li, Na, Ka, Mg, Ca, Ba, Cu, Ni, and Fe was demonstrated. Smaller and highly charged cations were found to be more effective for this recovery, and magnesium ions were the most effective of all the ions investigated.

A novel synthesis of trialkylstannyl- and silylpyridine derivatives through Diels-Alder reaction of 6H-1,3-oxazin-6-ones

A novel and convenient method for the synthesis of trimethylstannyl- and silylpyridine derivatives through Diels-Alder reaction of 6H-1,3-oxazin-6-ones with trialkylstannyl- and -silylacetylene derivatives was developped.

Regioselective aromatic substitution of 6,8-dihydroxy-4-ethoxycarbonyl-2H-isoquinolin-1-one derivatives using the stille coupling reaction

The novel synthesis of 6- or 7-aromatic substituted 2H-isoquinolin-1-ones, by two different routes is described. In the first route, 7-substituted derivatives were prepared by regioselective iodination at the 7-position of 6,8-dihydroxy-4-ethoxycarbonyl-2H-isoquinolin-1-one derivatives (1) followed by the Stille coupling reaction. In the second route, 6-subsutituted derivatives were prepared by the selective triflation of the 6-hydroxy group of 1 followed by the Stille coupling reaction.

A versatile new method for synthesis of isoquinolines; 6,8-dihydroxyisoquinoline derivatives from 6-methyl-1,3-oxazin-4-ones

A versatile method for synthesis of isoquinolone derivatives (4a-h) from 2-substituted 6-methyl-4H-1,3-oxazin-4-ones (1a-h) is described. Transformation of 1a-h with diethyl acetonedicarboxylate (2) in the presence of potassium tert-butoxide afforded 6-substituted 3-acetyl-5-ethoxycarbonyl-4-ethoxycarbonylmethylene-2-pyridones (3a-h) in excellent yields. Dieckmann-type cyclization of 3a-h with sodium ethoxide in ethanol produced the corresponding isoquinolone derivatives (4a-h) in good yields, respectively