The authors prepared ferulic acid from rice bran pitch which was discharged in a process of the production of edible oil from rice bran and synthesized ethyl 3- (4-geranyloxy-3-methoxyphenyl) -2-propenoate (EGMP) using ferulic acid. EGMP was found to be a chemopreventive agent toward colon cancer in the rats. The condensation products consisting of ferulic and gallic acids showed strong antioxidative effects. Alkyl ferulates showed antimicrobial activity. Amide derivatives of ferulic acid were recognized as compounds accelerating secretion of insulin. The authors also synthesized nine bisferuloyl-myo-inositols, consisting of ferulic acid and myo-inositol moieties, using four key intermediates. These compounds showed the inhibitory effects on generation of tumor promoter 12-O-tetradecanoylphorbor-13-acetate (TPA) -induced superoxide in differentiated HL-60 cells, the suppressive effects on TPA-induced Esptein-Barr virus activation and the suppressive effects on cyclooxgenase-2 promoter activity. The authors prepared the derivative 42 which has i) a polyoxyethylene chain and methoxy groups on the phenyl rings for metal coordination, ii) aromatic rings for a π-π or CH-π interaction, and iii) carboxylic acids as a hydrogen-bonding moiety.
Various spirobenzopyrans bearing crown ether moieties, namely, crowned spirobenzopyrans, were synthesized and their photochromism was examined in the presence of metal ions. The crowned spirobenzopyrans show facilitated photoisomerization reflecting not only the metal-ion binding ability of the crown ether moiety but also the metal-ion affinity of the phenolate anion moiety in the merocyanine form. When the interaction of metal-ion with the phenolate anion moiety is strong enough, thermal isomerization is observed. Furthermore, this interaction can induce negative photochromism upon UV irradiation. Thus, positive and negative photochromism switching of crowned spirobenzopyrans is possible through the interaction control of metal-ion with the phenolate anion and crown ether moiety.
The reaction of β-iodo allylic acetals with EtMgBr in THF afforded tetrahydrofuran derivatives. On the other hand, the reaction in DME provided (3-tetrahydrofuryl) methylmagnesium species that could be trapped by a variety of electrophiles. Treatment of arylmagnesium species with EtMgBr and iodoalkanes in THF afforded 2-aryltetrahydrofurans.nBu3MgLi induces facile iodine-magnesium exchange at -78°C. iPrnBu2MgLi is more reactive than nBu3MgLi, and this reagent accomplishes selective bromine-magnesium exchange at -78°C. This procedure was utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration at the double bond. The reaction of gem-dibromocyclopropanes with nBu3MgLi affords butylated cyclopropylmagnesium species that can be trapped with various electrophiles. The reaction of dibromomethylsilanes with nBu3MgLi in the presence of a catalytic amount of CuCN 2 LiC1 gives α-silylpentylmagnesium compounds that react with electrophiles such as acyl chlorides or α, β-unsaturated ketones to afford α- or γ-silyl ketones respectively. Treatment of dibromodisilylmethanes with Me3MgLi yields 1-bromo-1, 1-disilylethanes that can be converted into 1, 1-disilylethenes by dehydrobromination.
Optically active bis (oxazolinyl) phenyl (Phebox) was designed as an anionic N-C-N pincer ligand, and (Phebox) SnMe3 was prepared as its stable precursor. The aqua complexes, (Phebox) RhIIIX2H2O) [X=Cl, Br, F], [(Phebox) MII (H2O)] (BF4) [M=Pd, Pt] and [(Phebox) PtIV (H2O)] (BF4), were synthesized by the oxidative addition or transmetallation of RhI, PdII and PtII precursors with (Phebox) SnMe3 and subsequent ligand exchange reaction. X-ray structure studies revealed that the octahedral structure of RhIII complex is isosteric with the PtIV, and the PdII and PtII complexes are almost the same configuration with a square-planar structure. These aqua complexes acted as efficient catalysts for enantioselective allylation of aldehydes with allyltin reagents, hetero Diels-Alder reaction of Danishefsky's diene with glyoxylates and the aldol-type condensation of tosylmethyl isocyanide with aldehydes. While (Phebox) RhIII (SnMe3) Cl complexes catalyzed the Michael addition of α-cyanopropionates to acrolein.
Quinones are versatile compounds because the conjugated C=O and C=C double bonds are apt to undergo synthetically useful reactions such as 1, 3-dipolar cycloaddition, Diels-Alder reaction, and Michael addition. Diazoalkanes are also useful synthones as a carbene source and a typical dipole in 1, 3-dipolar reactions. Dipolar addition of quinones with diazoalkanes occurs at these double bonds to give oxadiazolines and pyrazolines as the primary adducts. Nitrogen release of these products yields zwitterion intermediates and homoquinones. The zwitterions easily reacted with common alcohols, α, w-diols, and oligoethylene glycols to provide acyclic, cyclic, and crown ether acetals, respectively. On the other hand, homoquinones exhibited photoinduced electron transfer reactions in the presence of some amine and arene donors to afford dimeric products, xanthylium salts, amine adducts, and so on. The enedione structure of homobenzoquinones allowed the [2+2] photocycloadditions with alkenes and alkynes to construct the strained tricyclic diones.