Thiourea fused γ-amino alcohol organocatalysts for asymmetric Mannich reaction of β-keto active methylene compounds with imines.

Catalytic functionality of new optically active thiourea fused γ-amino alcohols was examined in the asymmetric Mannich reaction of β-keto active methylene compounds with imines to afford chiral Mannich products, β-amino keto compounds, with continuous chiral centers, that are versatile synthetic intermediates for deriving various biologically active compounds. In particular, the thiourea fused γ-amino alcohols showed satisfactory catalytic activity in this reaction and afforded chiral Mannich products in excellent chemical yield (up to 88%) and stereoselectivities (up to  : /93 : 7 dr, up to 99% ee).

Synthesis of polynorbornadienes by ring-opening metathesis polymerization and their saturated derivatives bearing various ester groups and carboxyl groups.

Various symmetric and non-symmetric polynorbornadienes having a variety of ester groups and carboxyl groups were synthesized by ring-opening metathesis polymerization (ROMP) with Grubbs' third generation catalyst (G3 or [Ru]-III catalyst) in a controlled living manner from half-esters prepared by the selective monohydrolysis of symmetric diesters that we previously reported. The half-esters thus obtained can be directly submitted to ROMP with the G3 catalyst, leading to mostly the structure and narrow polydispersity indexes. The subsequent hydrogenation yielded saturated polymers, improving the thermostabilities according to the results.

New boro amino amide organocatalysts for asymmetric cross aldol reaction of ketones with carbonyl compounds.

Distinct types of new boron fused primary amino amide organocatalysts were designed and synthesized from commercially available amino acids. Their catalytic activities were investigated in asymmetric crossed aldol reaction of ketones with aromatic aldehydes to afford the corresponding chiral -aldol adducts with good chemical yields, moderate diastereoselectivity and good to excellent enantioselectivities (up to 94% yields, up to 90 : 10 dr, up to 94% ee).

Efficient and practical synthesis of monoalkyl oxalates under green conditions.

Monoalkyl oxalates are among the most important building blocks being applied to the synthesis of a variety of significant classes of compounds or applied to various cutting-edge reactions. However, their commercial availability is limited. Their synthetic methods are also limited because of the difficulty to synthesize them, and those hitherto reported are carried out in organic solvents often with the use of toxic reagents with mostly low to modest yields.

New small γ-turn type -primary amino terminal tripeptide organocatalyst for solvent-free asymmetric aldol reaction of various ketones with aldehydes.

New small γ-turn type -primary amino terminal tripeptides were synthesized and their functionality as an organocatalyst was examined in the asymmetric aldol reaction of various ketones with different aromatic aldehydes under solvent-free neat conditions to afford the desired chiral -aldol products in good to excellent chemical yields, diastereoselectivities and enantioselectivities (up to 99%, up to  : /13 : 87 dr, up to 99% ee).

New aspect of photophysics of 7,7,8,8-tetracyanoquinodimethane and its solvated complexes: intra- inter-molecular charge-transfer.

We performed laser-induced fluorescence (LIF) spectroscopy of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its solvated complexes with acetonitrile (ACN) and benzene (Bz), under the jet-cooled gas-phase condition. We also carried out fluorescence and its time profile measurements in TCNQ/Bz/hexane solution to compare with the gas-phase results. The LIF excitation spectrum of the S (ππ*)-S electronic transition of TCNQ monomer exhibited unusual vibronic structure with the maximum intensity at ∼3000 cm above the band origin.

Simple primary β-amino alcohols as organocatalysts for the asymmetric Michael addition of β-keto esters to nitroalkenes.

Simple primary β-amino alcohols act as an efficient organocatalysts in the asymmetric Michael addition of β-keto esters with nitroalkenes affording highly pure chiral Michael adducts. Also, both enantiomers of the adducts were obtained, depending on the specific catalyst used and reaction temperature.

Simple organocatalyst component system for asymmetric hetero Diels-Alder reaction of isatins with enones.

A simple two catalyst component system consisting of primary β-amino alcohols as a catalyst and amino acids as a co-catalyst put together works as an efficient organocatalyst system in the hetero Diels-Alder reaction of isatins with enones to afford the chiral spirooxindole-tetrahydropyranones in good chemical yields and stereoselectivities (up to 86%, up to 85 : 15 dr., up to 95% ee).

A new algorithm for predicting splice site sequence based on an improvement of categorical discriminant analysis.

The splicing signals which govern the excision of introns are not yet well explained, since actual splice site sequences are to some extent different from the generally accepted consensus sequences. While a quantification method (categorical discriminant analysis: CDA) has been proposed to analyze splice site signals, sample sequences lying in the overlapping region of sample scores are not discriminated well by CDA, thus limiting the predictive ability of this analytical technique. In this paper, we propose a method to improve the performance of CDA, which is applicable to the analysis of 5'-splice site signals in various mammalian genes.