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1-(2-Naphthalenecarboxy)- n -( p -substituted benzenecarboxy)oxaalkanes (2NP n X, X=H, Cl, CF 3 , CN; n =5, 6) as fluorescent sensors by exciplex emission for metal ions were synthesized. We investigated the relationship between the substitution effects and the metal ion recognition. Before the metal salts were added, the substitution effect was found. The fluorescence quantum yields ( Φ f ) decrease as the electronegativity of the p -substituent of the acceptor benzoate increases. 2NP n CN ( n =5, 6) with the most negative free energy of electron transfer (Δ G ET ) showed the most efficient quenching and exciplex emission. When Li + , Na + , K + and Mg 2+ were added to the acetonitrile solution of 2NP n X (X=H, Cl, CF 3 , CN; n =5, 6), the shape and intensity of the fluorescence spectra did not change. However, the spectra of all the 2NP n Xs significantly changed with the addition of Ca 2+ and Ba 2+ . Especially, due to the large fluorescent enhancement factor of 2NP n CN ( n =5, 6) for Ca 2+ , they are well-suited for use as a fluorescent chemosensor for Ca 2+ .

N -ethyl-1-naphthalenecarboxamide (1NEa) was synthesized as a reference compound of the 1, n -bis(1-naphthalenecarboxamido)oxaalkanes (1NSN and 1NLN) having two naphthalene rings as fluorescent chemosensors for metal ions using intramolecular excimer emission. However, large changes in the fluorescence spectra of 1NEa having only one naphthalene ring as well as 1NSN and 1NLN were observed with the addition of some metal ions. Therefore, the ab initio molecular orbital calculations (Gaussian 98) using both the Hartree–Fock SCF and density functional theory methods with 6-31G and 6-31+G(d) basis sets were carried out for 1NEa and its metal complexes to investigate the complexing behavior. The results of the molecular orbital calculations suggest that 1NEa can form a complex with a metal ion by coordination with both the carbonyl oxygen of the amide group and π-electrons of the naphthalene ring.

1, n -Bis(1-naphthalenecarboxy)oxaalkanes (1NP n N, n =1–6) and 1, n -bis(2-naphthalenecarboxy)oxaalkanes (2NP n N, n =1–6) as fluorescent sensors by excimer emission (EX) for metal ions were synthesized. We investigated the relationship between the length of the polyether chain and the metal ion recognition of NP n N (NP n N=1NP n N or 2NP n N, n =1–6) in acetonitrile solution, and the influence of the naphthalene substitution position (α-position or β-position) for metal ion recognition. Changes in the fluorescence spectra of NP n N ( n =1–3) were not observed by the addition of alkali and alkaline earth metal salts. However, the spectra of NP n N ( n =4–6) were changed by the addition of calcium and barium salts. Especially in NP n N ( n =5, 6), the changes in the shape and intensity of the fluorescence spectra were great. The values of log K for Ca 2+ and Ba 2+ were 2NP6N>1NP6N>2NP5N>1NP5N. In the cases of same length of the polyether chain, 2NP n N is an excellent fluorescent chemosensor for Ca 2+ and Ba 2+ , better than 1NP n N.

The diastereoselectivity in the conjugate addition of organocopper reagents to γ-aryl α,β-unsaturated carbonyl derivatives 8–14 was investigated. The syn -diastereoselectivity was obtained irrespective of the reagents type in the addition of 8, while the anti -diastereoselectivity was obtained in the addition of 10–14 with RCu and RCu(CN)Li (R=Me and Bu) and the syn -selectivity was produced in the addition of 10–14 with R 2 CuLi and R 2 Cu(CN)Li 2 . The reagent controlled and substrate dependent diastereoselectivity are explained by two different reaction pathways: either π-complex formation or ordinary nucleophilic addition. Reduction potentials of the Michael acceptors and electron donating ability of organocopper reagents control the reaction pathway.

The novel glycosphingolipid, SEGLx (Gal beta 1-4(Fuc alpha 1-3)Glc beta 1-3Gal beta Cer), which was identified by us (Kawakami Y, et al. (1993) J Biochem 114: 677-83), shows a characteristic spectrum on 1H-NMR analysis, in which the anomeric proton resonances of a reducing end galactose and a glucose are split. To elucidate the structural characteristics of SEGLx, we determined its three-dimensional (3D) structure by means of computer simulation, involving such techniques as molecular mechanics (MM2), the semiempirical molecular orbital method (AM1), molecular dynamics (Amber), and computer 3D modelling. With the hypothesis that all OH group(s) of a ceramide participate in intramolecular hydrogen bonds, two kinds of stable conformers, horizontal and right-angled ones, were formed, depending on the ceramide species. The present findings suggest that the chemical species of both the long chain base and fatty acid moieties, mainly the occurrence of OH group(s), affect the chemical shifts of the anomeric proton resonances not only of the reducing terminal galactose but also the penultimate glucose through the formation of intramolecular hydrogen bonds. Computer simulation through theoretical calculation and 3D modelling was shown to be the best means of confirming the results obtained by experimental analysis.

New naphthalene derivatives (1NSN, 1NLN, 1NE and 1NcrownN) as fluorescent chemosensors for metal ions using excimer emission were synthesized. We investigated the metal ion recognition of 1NSN, 1NLN, 1NE and 1NcrownN. Large changes in the fluorescence spectra of not only 1NSN and 1NLN but also 1NE were observed with the addition of magnesium ion. However, changes in the fluorescence spectra of 1NcrownN were not observed with the addition of alkali and alkaline earth metal ions.

The diastereoselectivity in the conjugate addition of organocopper reagents to γ-aryl α,β-unsaturated carbonyl derivatives 8–14 was investigated. The syn -diastereoselectivity was obtained irrespective of the reagents type in the addition of 8, while the anti -diastereoselectivity was obtained in the addition of 10–14 with RCu and RCu(CN)Li (R=Me and Bu) and the syn -selectivity was produced in the addition of 10–14 with R 2 CuLi and R 2 Cu(CN)Li 2 . The reagent controlled and substrate dependent diastereoselectivity are explained by two different reaction pathways: either π-complex formation or ordinary nucleophilic addition. Reduction potentials of the Michael acceptors and electron donating ability of organocopper reagents control the reaction pathway.

trans-5-Aryl and 5-cyclopropyl derivatives of 2-isoxazolin-4-ol were conveniently prepared from trans-2-aryl- and 2-cyclopropyl-3-benzoyloxiranes and hydroxylamine hydrochloride in the presence of pyridine via an intramolecular opening of oxirane by the oxygen nucleophile of the oxyimino group.

New naphthalene derivatives (1NSN, 1NLN, 1NE and 1NcrownN) as fluorescent chemosensors for metal ions using excimer emission were synthesized. We investigated the metal ion recognition of 1NSN, 1NLN, 1NE and 1NcrownN. Large changes in the fluorescence spectra of not only 1NSN and 1NLN but also 1NE were observed with the addition of magnesium ion. However, changes in the fluorescence spectra of 1NcrownN were not observed with the addition of alkali and alkaline earth metal ions.

1-(1-naphthalenecarboxy)-n-(p-cyano benzenecarboxy)oxaalkanes (1NPnCN, n = 1–6) as fluorescent sensors by exciplex emission for metal ions were synthesized. we investigated the relationship between the length of the polyether chain and the metal ion recognition of 1NPnCN (n = 1–6). Changes in the fluorescence spectra of 1NPnCN (n = 1–4) were not observed by the addition of calcium and barium salts. However, the spectra of 1NPnCN (n = 5, 6) were changed.

1,n -Bis(1-naphthylcarboxy)oxaalkanes (1NPnN, n = 1, 2, 3, 4, 5, 6) as fluorescent sensors by excimer emission for metal ions were synthesized, and the complexation of 1NPnN with alkali and alkaline earth metal ions in acetonitrile was investigated. Alkaline earth metal cations suppress or enhance the fluorescence remarkably, depending on the cation size and the length of polyether chain.

An intercomparison of the NMR data for the methyl protons in a series of thirty-seven alkaloids of the Veratrum group provides additional support for previous proposals regarding the β-configuration of the C-27 methyl group in all of these compounds and the cis A/B ring fusion in the sabine derivatives. Furthermore, the variations of the chemical shift for the C-21 methyl protons strongly suggest that the conformation of the D-ring is changed upon formation of the D- ortho acetate grouping.

The structures and absolute configuration of α-kessyl alcohol (I) and kessyl glycol (II), sesquiterpenic constituents of Japanese valerian roots, have been established on the basis of chemical and spectroscopic data.

The pure quadrupole resonance frequencies of 81Br were determined for various bromotropolones at liquid nitrogen temperature. Each of monobromotropolone isomers shows a single resonance line, indicating that all bromine atoms in the crystals are equivalent. 3,5-Dibromotropolone gives rise to two resonance signals in agreement with the presence of two kinds of non-equivalent bromine atoms in a molecule. 3,7-Dibromotropolone yields a closely spaced doublet presumably due to the crystal effect. Only one line attributable to bromine atoms at position 5 was observed for 3,5,7-tribromotropolone. The ionic character of CBr bonds in these molecules can be explained by means of the inductive effect.

The reaction of isoflavanone oxime (III), 7-methoxyisoflavanone oxime (IV), and 4′,7-dimethoxyisoflavanone oxime (V) with lithium aluminum hydride in ether for 20 hr under refluxing gave 3-phenyl-2,3,4,5-tetrahydro-1,5-benzoxazepine derivatives (XVII, XVIII and XIX) but not the expected 4-aminoisoflavans. When a similar reaction was carried out using flavanone oxime and 7-methoxyflavanone oxime, only 4-aminoflavans were obtained, and the rearrangement reaction observed in isoflavanone oximes did not occur. Therefore, it may be considered that, in the reaction of chromanone oximes and lithium aluminum hydride, the position (C2 or C3) and the size of the substituent exerts a remarkable influence on the rearrangement reaction, while the methoxyl group at the 7-position (para position to the oximino group) has little effect.

The reaction of nitrous acid and three 4-aminoisoflavan hydrochlorides (III, IV, and V) obtained by the catalytic hydrogenation of isoflavanone oximes, and the hydroboration of three isoflavenes (XII, XIII, and VIII), were investigated in the hope of finding a general method of synthesizing trans-isoflavan-4-ols. The reaction of III and IV with nitrous acid afforded the corresponding trans-4-ols, though in a poor yield, but that of V produced no expected compound, the corresponding isoflavene (VIII) being obtained instead. The hydroboration of XII, XIII, and VIII afforded the corresponding trans alcohols (VI, VII, and XIV) in good yields. In addition, it became clear that 4-aminoisoflavans obtained by the catalytic reduction of the oximino compounds possess the 3,4-cis configuration.

The acid catalyzed ring opening of trans-stilbene oxide was investigated in DMSO, DMF, THF, and dioxane and the products, meso and dl-hydrobenzoins and diphenylacetaldehyde, were determined. In the solvents of high polarity, inversion of configuration was observed in most products, and the opposite was true in the solvents of low polarity. There was no direct relation between rearrangement products and polarity of solvents.

The irradiation of a benzene solution of 2,2,4,4-tetraacylthietane 1-oxides, which had been prepared from dimedone-aldehyde derivatives with SCl2, followed by oxidation with peracid, was carried out to give the corresponding 1,1,2,2-tetraacylcylopropanes(4) or a mixture of 4 and the corresponding dihydrofuran derivative, depending on the C3 substituent on the 1-oxides and wavelength.