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[structure: see text] Carboxamides possessing naphthalene rings connected by multiple iminodicarbonyl linkers were synthesized. These molecules forced the naphthalene rings to be placed in the positions facing each other, and they form helical foldamers both in solution and in the crystalline state. Their folding structures were investigated by single-crystal X-ray analysis and (1)H NMR spectroscopy. Their absorption and fluorescence spectra showed a red shift as the number of naphthalene moieties increased. This remarkable change is based on the intramolecular interaction between naphthalene moieties. Helicity of the foldamer can be controlled by the introduction of chiral auxiliaries at imide nitrogen atoms, which results in an observation of induced circular dichroism.

The photocycloaddition reaction of naphthyl-N-(naphthylcarbonyl)carboxamides (1) was examined under argon and oxygen atmospheres. In addition to the [2 + 2] and [4 + 4] cycloadducts, 3 and 4, respectively, novel 1,8-epidioxides (5) were formed under oxygen atmosphere. The transient absorption at lambda max of 360 nm with the lifetime of 360 ns was observed by laser flash photolysis of 1c and was interpreted as the absorption of biradical intermediate 2. On the basis of the anti stereochemistry of 5, which was different from that of the major [4 + 4] cycloadducts, syn-4, it was deduced that equilibrium between biradical intermediates syn-2 and anti-2 would exist. Retro [2 + 2] cycloaddition of 3 was responsible for the efficient trapping of the biradical intermediate with molecular oxygen. The photocycloaddition of the anthryl derivatives, 9-anthryl-N-(methylethyl)-N-(naphthylcarbonyl)carboxamides (7), afforded the [4 + 4] cycloadducts (8) exclusively in a quantitative yield even under oxygen atmosphere. The absence of trapping with molecular oxygen was interpreted to be due to the lack of retro [4 + 4] cycloaddition of 8.

A novel clathrate host, N,N‘-bis(2-tert-butylphenyl)pyromellitic diimide (1), was designed to create a sandwich structure without using cyclophanes nor the acyclic compounds. In the host−guest crystal, the host molecule is sandwiched between two aromatic guest molecules. The inclusion experiment was performed by recrystallization of 1 from chloroform in the presence of the guest at room temperature to give the clathrate compounds. Phenols (phenol, p-cresol, α-naphthol, β-naphthol, catechol) and indoles (indole, 3-methylindole, 4-methylindole, 5-methylindole) were included in the clathrate compounds, and the host/guest ratio 1:2 was observed in all cases. To explain the mechanism of the self-assembly to the piled sandwich structure, X-ray analysis of the single crystals was performed in all cases. Further, charge-transfer complexation, hydrogen bonding and dipole−dipole interaction were investigated using UV, IR, differential scanning calorimertry (DSC), and AM1 calculation. The order of the decomposition ...

The first tandem radical cyclization of linear homoallylic xanthates was explored. Homoallylic santhates prepared from α,β-unsaturated esters were easily cyclized by tin hydride with an radical initiator to give the corresponding thionolactone annulated cyclopentane skeleton in a high yield. The stereochemistry of cyclized products was also discussed. Thionolactones obtained were oxidized chemoselectivity with m-CPBA under neutral condition to afford γ-lactones in a high yield

Octahomotetraoxacalix[4]arenes bearing long alkyl chains on their lower rim were prepared. Ester 4a existed in a 1,2-alternate conformation in its crystal structure, which was examined by single-crystal X-ray diffraction analysis. To prepare liquid crystalline materials possessing calixarene moieties by self-assembling, carboxylic acid derivatives 5 were synthesized. Among them, 5c, the octadecyloxy derivative, showed smectic liquid crystal phase. Homooxacalixarenes 5 also formed liquid crystal phases with longer layer distances when two equivalent moles of 1,2-ethylenediamine were added as a linker. These phases were investigated with X-ray diffraction, differential scanning calorimetry, and polarized optical microscopy.

Conformational control of a cyclophane with intermolecular hydrogen bonding was accomplished through the first synthesis of a carbamoyloxa-bridged cyclophane 3, with the result that the crystal structures of two isolable conformers 3a and 3b were elucidated to be anti-(E,E) and anti-(Z,Z) by X-ray analysis. The convenient conversion of 3a to 3b was carried out with hydrogen bonding assisted by polar solvents

Isolement et caracterisation d'une toxine a proprietes antitumorales, a partir d'une eponge de l'espece Dragmacidon. Pour caracteriser cette nouvelle molecule appelee Dragmacidine, les techniques classiques d'investigation ont ete utilisees: Spectrometrie RMN, IR, UV… Des essais de toxicite sur des cellules leucemiques de souris ont ete effectues in vitro