Intramolecular Nucleophilic Acyl Substitution Reaction of 3,4-Alkadienyl Carbonates Mediated by Ti(O-i-Pr)(4)/2 i-PrMgCl Reagent. Efficient Synthesis of Optically Active beta,gamma-Unsaturated Esters with an alpha-Substituent

Treatment of 3,4-alkadienyl carbonates 2a-i with a low-valent titanium reagent diisopropoxy(eta(2)-propene)titanium (1), readily generated by the reaction of Ti(O-i-Pr)(4) with 2 i-PrMgCl, resulted in an intramolecular nucleophilic acyl substitution (INAS) reaction to afford vinyltitanium compounds 3 which, in turn, reacted with H(3)O(+), D(2)O, or iodine to give alpha-substituted beta,gamma-unsaturated esters 4 in good to excellent yields. The olefin moiety of the hydrolysis product 4 has (Z)-geometry mainly except for 4h. Starting from chiral 2f or 2g, the reaction proceeded stereospecifically to give optically active alpha-substituted beta,gamma-unsaturated ester 4f or 4g having (Z)-olefin geometry exclusively.     

Total synthesis of merrilactone A

Merrilactone A (1) has been shown to possess neurotrophic activity and thus is expected to hold therapeutic potential in the treatment of neurodegeneration diseases. In this paper, we report the total synthesis of (+/-)-1, employing, as key steps, a novel desymmetrization protocol of meso-diketone to construct the core cis-bicyclo[3.3.0]octyl system of 1 (3 --> 2) and a radical cyclization to install the highly congested C9-quaternary carbon (16 --> 17).     

Surface structures of adsorption layers of sodium hyaluronate and bovine serum albumin complexes on poly(γ-methyl-l-glutamate) film and their surface properties

Two-dimensional structures and characteristics of the complexes between sodium hyaluronate (NaHA) and bovine serum albumin (BSA) were studied by using a quartz crystal microbalance method and an atomic force microscope (AFM). NaHA did not adsorb on poly(-methyl-l-glutamate) (PMLG) film. On the other hand, the complexes adsorbed on it and the adsorption behaviors were found to be Langmuir types. With increasing weight ratio of BSA to NaHA, W _BSA, the adsorption constants K decreased and the saturated adsorption masses increased. The adsorbed complexes were spherical particles and at saturated adsorption states they covered compactly on the PMLG film. The mean diameters d _AFM estimated from the topographic images decreased from 70 to 54 nm with increasing W _BSA. The adhesion force F _ad and the frictional force F _f between the complex layers and the AFM tip were obtained by using the contact mode of the AFM. With increasing W _BSA, the values of F _ad decreased and the values of F _f increased. Compared with the frictional coefficient of the NaHA adsorption layer on the BSA monolayer, the values for the NaHA–BSA complex layer were found to be much higher.     

Smectic layer structure of ferroelectric liquid crystal formed between fine polymer fibres

This paper describes the alignment of ferroelectric liquid crystal (FLC) structures formed between aligned polymer fibres, where the FLC smectic layers are determined by polarising microscopy and X-ray diffraction. The FLC/polymer composite films were formed from a nematic phase FLC/monomer solution using a photopolymerisation-induced phase separation method. It was found that bending of the FLC smectic layers was induced in both the film plane and the cross-sectional plane at the phase transition from smectic A to chiral smectic C of the FLC material. The light transmittance properties of the composite film between crossed polarizers was analysed by light propagation simulation in several optical anisotropic media, based on the evaluated smectic layer model.     

Unprecedented double C-C bond cleavage of a cyclopentadienyl ligand

Double C-C bond cleavage of a cyclopentadienyl ligand proceeded to titanacyclopentadienes when 2 equiv of nitriles were added and the resulting two-carbon unit and three-carbon unit were converted into a benzene derivative and a pyridine derivative, respectively, in one-pot.