Enantioselective synthesis of attenols A and B

[reaction: see text] Enantioselective synthesis of attenols A and B was accomplished by using diastereoselective hydroboration, Lindlar reduction, and acid-catalyzed acetal formation.     

Belt‐Shaped Cyclonaphthylenes

The recent development of cyclo‐para‐phenylenes has demonstrated the feasibility of radial π systems in nanohoop structures, especially in the crystalline state. However, in contrast to macrocyclic molecules with benzene units, which have a several‐decades‐long history, macrocycles composed solely of naphthylene units (the smallest acene) have been much less explored. Although two examples of cyclonaphthylenes have been reported to date, neither possesses a radial π system. We herein report the first example of belt‐shaped cyclonaphthylenes with curved π systems. The molecule, [8]cyclo‐amphi‐naphthylene, is linked at the 2,6‐positions of the naphthylene units, thus affording belt‐shaped molecules. Although the molecular structures are flexible, which allows for rotation of the naphthylene units in solution, they can be rigidified with the aid of methylene bridges to afford persistent molecular structures in solution.     

Halichonines A, B, and C, novel sesquiterpene alkaloids from the marine sponge Halichondria okadai Kadota

Novel sesquiterpene alkaloids, halichonines A (1), B (2), and C (3), were identified from the marine sponge Halichondria okadai Kadota. By spectroscopic analyses and synthesis, their structures were revealed to include a 6,6-bicyclic ring system and two prenylated amine moieties. In addition, 2 induced apoptosis in HL60 human leukemia cells.     

Enzymatic resolution of flavanone oximes

The optically active (R)- and (S)-flavanones were prepared by an enzymatically enantioselective hydrolysis of (±)-flavanone oxime O-acylates employing lipases, followed by hydrolysis with acid.     

The boundary between the spin-glass and ferromagnetic states of the bond-random Ising model in the square lattice at T = 0

The bond-random (±J) Ising model in the square lattice is considered in the square cluster approximation. The boundary between the ferromagnetic and spin-glass states at T = 0 is obtained as the transition point from the asymmetric distribution of the effective fields to the symmetric distribution. The concentration of this transition, P_FG is obtained by solving the integral equation for the distribution function of the effective fields.     

Silver(I) coordination polymers of fluorescent oligo(phenylenevinylene) with pi-pi stackings: luminescence and conductivity

Three luminescent silver(I)-oligo(phenylenevinylene) complexes, [Ag2(bmsb)(ClO4)2] (1), [Ag2(bmsb)(H2O)4](BF4)2 (2), and [Ag2(bdb)(CF3SO3)2] (3) (bmsb = 1, 4-bis(methylstyryl)benzene, bdb = 4,4'-bis(2, 5-dimethylstryryl)biphenyl), have been synthesized and structurally characterized. Complexes 1 and 2 are 2D networks with unique metallocyclophane motifs. Complex 3 affords a 2D zigzag sheet, in which silver triflates form tubelike double chains and bdb molecules act as linkages. Complex 2 exhibits high electric conductivity because of columnar aromatic stackings formed through intra- and intermolecular pi-pi interactions. Complexes 1-3 in the solid state exhibit luminescence, of which excitation and emission maxima are shifted to longer wavelength as compared to those of the corresponding metal-free ligands.     

A facile synthesis of [3ncyclophanes,in which aromatic rings are connected with -CH2CO-CH2- bridges

The title compounds, I, were synthesized by the dialkylation of TosMIC, II, with appropriate bis (halomethyl) compounds, III, under phase-transfer condition, followed by acid hydrolysis.     

Caldorin,a new polyketide from the marine cyanobacterium Caldora penicillata

A new polyketide with a cis-fused decalin ring scaffold, caldorin, was isolated from the marine cyanobacterium Caldora penicillata. The gross structure and relative configuration were elucidated by spectroscopic analyses. We also clarified that caldorin is a weak SOAT inhibitor and moderate osteoblast differentiation inhibitor. On the other hand, caldorin did not exhibit cytotoxicity against either HeLa or HL60 cells.