岸川 圭希

Compounds 1, N, N-bis{4-[4-(4-alkoxybenzoyloxy) benzyloxy] benzoyl} alkylamines, were designed and synthesized as "tuning fork''-shaped molecules, and their properties were investigated by polarized light microscopy and differential scanning calorimetry, and the layer distances were measured by X-ray diffraction. The observed smectic A liquid crystal phases indicated the existence of large hysteresis in XRD. The multiple broad peaks of the layer distances originated in the plural extent of interdigitation of the alkyl chains between the layers, and the layer distances strongly depended on the hysteresis. Further, the chiral and racemic liquid crystalline compounds, (R)-1k and rac-1k, showed a clear difference in the interlayer interdigitations in their mesophases.

Previously we reported regioselective formation of dianions derived from liner nitroalkanes in the presence of n-BuLi and HMPA. The formation of nitroalkane dianions either α, α- or α, β-dianions depended on the order of addition of reagents. However, the usage of a carcinogen suspected compound like HMPA is undesirable. Therefore we re-investigated the new combination of bases and aprotic dipolar solvents other than HMPA. After exploration of a variety of their combination, it was found that the combination of LDA and DMPU resulted in the formation of α, β-dianion with the best regioselectivity the ratio of α- to β-adduct was 1 to 14 in the reaction of nitroethane with benzaldehyde. © 2002, The Chemical Society of Japan. All rights reserved.

A mild and convenient method for generation of nitrile oxide is established by iodosylbenzene oxidation of aldehyde oximes. Aldehyde oximes were converted to furoxans in almost quantitative yields via dimerization of corresponding nitrile oxides upon oxidation. When the oxidation was carried out in the presence of alkene and alkyne dipolarophiles, isoxazolines or isoxazoles were obtained in good yields. © 2002, The Chemical Society of Japan. All rights reserved.

Control of three modes of intramolecular reactions, [2+2] and [4+2] cycloadditions, and Type-II cyclisation, is attempted in the photochemical reaction of N-(naphthylethyl)prop-2-enamides. The reactions are affected by the enamide substituents and the sensitisation conditions used. Acryloyl derivatives undergo [2+2] cycloaddition and Type-II cyclisation. The two reactions occur selectively depending on the sensitiser used, benzophenone sensitisation affording the [2+2] cycloadducts whereas the Type-II cyclisation products are obtained exclusively by benzene sensitisation. In contrast, photolysis of cinnamoyl derivatives results in the formation of [4+2] cycloadducts. © 2001 The Royal Society of Chemistry.

Guest inclusion abilities of two rotamers, anti- and syn-N,N'-bis-(2-tert-butylphenyl)naphthalene-1,4,5,8-tetracarboxylic diimides 1 and 2, were investigated. Rotamers 1 and 2 were synthesised from 2-tert-butylaniline and naphthalene-1,4,5,8-tetracarboxylic dianhydride and separated by conventional column chromatography on silica gel. Recrystallisation of 1 from chloroform in the presence of a guest molecule (3 mole equivalents) was performed, and 15 guest molecules were included with a variety of host:guest ratios, 1:1 (chloroform, pyridine, 4-picoline, benzene, quinoline, diphenylacetylene, naphthalene, and p-toluidine), 1:2 (phenol, 3-ethylphenol, 4-methoxyphenol, indole, 5-methylindole, and tetrathiafulvalene), and 1:4 (benzothiazole). In contrast, 2 showed no inclusion of guest molecules under the same conditions as those applied to 1. In order to investigate the intermolecular interaction in the crystalline state of 1, 2 and 1.(indole)(2), X-ray diffraction of single crystals was measured and these structures were compared.

Intramolecular diastereoselective [4 + 4] photocycloadditions of acyclic imides 1a and 1b possessing anthracene and naphthalene moieties were carried out in the solid state and in solution. For 1a, novel reversal of diastereoselectivity was observed on changing the reaction phase. The diastereomeric excess was changed from -60% de in the solid state at 60 degreesC to 70% de in acetone at -78 degreesC. Almost 100% de was observed for the solid-state photocycloaddition of 1b. The reactivity of 1a in the solid state was discussed based on its single crystal X-ray analysis.

The new type channel structure in the chemistry of cholic acid was created by the protection of both end (the hydroxy group at the 3-position and the carboxy group at the 23-position) of cholic acid. The inhibition of the intermolecular hydrogen bonding existing in cholic acid at these positions altered the crystal structure completely.

The new type channel structure in the chemistry of cholic acid was created by the protection of both end (the hydroxy group at the 3-position and the carboxy group at the 23-position) of cholic acid. The inhibition of the intermolecular hydrogen bonding existing in cholic acid at these positions altered the crystal structure completely.

Anti- β -stannyl- α -substituted carbonyl compounds were completely converted to its syn-analogues, and each diastereomer was oxidized to its β -hydroxylated analogues with retention of the stereochemistry.

Facile regioselective macrocyclization of methyl cholate (1) using dimethyl alpha,alpha,alpha',alpha'-tetramethyl-m-xylylenedicarbamate (2) by trans-esterification was achieved, in refluxing toluene (0.004 M), using 3% of SnCl2 and 1% of glycoluril as an additive. After a reaction time of 2 hours, the kinetically favorable 3 was obtained selectively in excellent yield (94%). Conversion of the 16-membered 3 to the 18-membered cyclophane 4 was achieved by establishing an equilibrium (7 days),to give the thermodynamically stable 4 in practical yield (68%). This mild conversion of the regiochemistry of the steroidal macrocycles is remarkable as a characteristic of the carbamoyloxa-bridged cyclophanes. The new steroidal carbamoyloxa-bridged cyclophanes is the first example of a pair of the regioisomeric steroidal cyclophanes.

Steroidal triply-bridged cyclophanes are synthesised using cholic acid derivatives as bridge units; cyclophane 3 moderately binds to organic guest molecules and enantioselectively binds to N-Z-phenylalanine.

In order to elucidate the conformation of acylurea which possesses intramolecular hydrogen bonding between the carbonyl and NH groups, the relation between solvent polarity [ET(30)] and specific rotation of 2,6-bis(ureidocarbonyl)naphthalene 1 was examined. A good Linear relationship was observed, except for solvents with a carbonyl functionality. Some of these solvents formed molecular complexes with 1 (molar ratio of 1:solvent, 1:2). Single crystal X-ray diffraction analysis of the molecular complex of 1 with ethyl acetate disclosed that the intramolecular hydrogen bonding was absent due to the intermolecular hyrdrogen bonding with ethyl acetate. In contrast, 2,4'-bis(ureidocarbonyl)benzophenone 2 formed 1:1 complexes with carbonyl compounds, and the bulkier 2,6-bis(ureidocarbonyl)naphthalene 3 could not form complexes with them.

Norcaradiene derivatives 1, 5-(1-benzyloxycarbonyl-2-methyl-1-propenyl)-3-oxatricyclo[4.4.0.0^1,5]deca-7,9-dien-4-one, showed a restricted rotation in the ¹H NMR spectra. VT ¹H NMR measurements in CDCl₃ revealed the existence of two rotamers at low temperature with ΔG^≠ of 11.5 (250 K), 12.1 (263 K), and 13.9 kcal mol⁻¹ (296 K) for norcaradienes with R = H, Me, and t-Bu, where R is the para substituent of the benzyloxy group, respectively. This restricted rotation was stopped in CDCl₃ at ambient temperature by introducing intramolecular hydrogen bonding via reducing of the lactone moiety to the corresponding lactols. The observed conformational locking due to the intramolecular hydrogen bonding was unlocked by solvation, resulting in the formation of three conformers in methanol-d₄ and dimethyl-d₆ sulfoxide. VT ¹H NMR measurements of the lactol derivative in dimethyl-d₆ sulfoxide showed that two of the conformers interconverted with ΔG^≠ of 17.4 kcal mol⁻¹.

Resolution of racemic amides was achieved by column chromatography on silica gel modified with a chiral acylurea which has two (S)-1-phenylethyl moieties in a pseudo-C2symmetric position around an axis of the urea-carbonyl. ? 1995.

The relation between solvent polarity and the chemical shifts of two diastereoisomeric N-cyclopropylcarbonylureas 1 and 2 was examined to elucidate their conformations in solution. In non-polar solvents, where intramolecular hydrogen bonding was playing an important role, their conformations were estimated to be similar to that of 1 in its crystalline state.