Hajime Takahashi

Direct C-C bond formation between thymine derivatives and naphthalene through [2+2]-photocycloaddition

In contrast to our previous findings that UV-irradiation of 1,3-dimethylthymine (la) with naphthalene (2) underwent 1,4-cycloaddition to give an ethenobenzoquinazoline derivative, UV-irradiation of a mixture of la and 2 in the presence of piperylene preferentially underwent 1,2-cycloaddition to give cis-tetrahydronaphthocyclobutapyrimidine in high stereoselectivity. Similar irradiation of 1,3-dimethyluracil and its derivatives (1) with substituents at C-5 gave the corresponding cis-1,2-adducts (3) in fair yields.

Crystal structures of coumarin-3-carbamate derivatives with herbicidal activities

Coumarin-3-carbamate derivatives were prepared by the reaction of alcohols with coumarin-3-carbonyl azide. The testosterone derivative has herbicidal activities, but the benzene derivative does not have the activities. The crystal structures of two coumarin-3-carbamate derivatives were analyzed by X-ray crystallography. The crystals of the testosterone derivative had intermolecular N-H···O, C-H···O, and C-H···π interactions.

SYNTHESIS AND PROPERTIES OF PET FLUOROIONOPHORE HAVING 1-PYRIDIN-2-YLPIPERAZINE GROUP

9-[4-(2-pyridinyl)-1-piperazinyl]methyl]anthracene (1) and 9,10-bis[[4-(2-pyridinyl)-l-piperazinyl]methyl]anthracene (2) were synthesized as a fluorescent PET sensor. The sensor functions as an off-on-off fluorescence switch for proton.

5-Benzyl-1,3,5-trimethylpyrimidine-2,4,6(1H,3H,5H)-trithione

Barbiturates act as central nervous system depressants and produce a wide spectrum of effects, from mild sedation to anesthesia (Bideau et al., 1976; Gotthardt et al., 1980). Some are also used as anticonvulsants. Although a number of barbiturates have been studied, there have been only a few studies of their sulfur analogs (trithiobarbiturate) (Greenberg et al., 2000) and while most crystals of barbiturates are colorless those of thiobarbiturates, such as (I), are usually colored.

Synthesis and complexation behavior of 4,10-bis(1-pyrenylmethyl)-1,7-dioxa-4,10-diazacyclododecane

Fluorescent photoinduced electron transfer (PET) fluoroionophore (2c) that consists of diaza-12-crown-4 and two 1-pyrenylmethyl pendants shows fluorescent enhancement with various metal cations. The sensor (2c) exhibited Zn 2+ selectivity and in the presence of this cation the host fluorescence was increased by a factor of 38.