Haruo Matsuyama

Heat capacity measurements and phase transition of crystalline 4,4″-difluoro-p-terphenyl

Abstract The heat capacity of 4,4″-difluoro- p -terphenyl was measured between 8 and 303 K by adiabatic calorimetry. A phase transition associated with molecular twisting was observed as a sharp peak at (127.05 ± 0.05) K. The enthalpy and the entropy of transition were determined as (180 ± 20) J mol −1 and (1.41 ± 0.15) J K −1 mol −1 , respectively. It is pointed out that this phase transition lies in the border region between an order-disorder and displacive-type transition under normal pressure. The apparatus used for calorimetry is described.

An in Vitro System of Indole-3-Acetic Acid Formation from Tryptophan in Maize (Zea mays) Coleoptile Extracts

The formation of a product from tryptophan that had the same retention time as that of authentic indole-3-acetic acid (IAA) on high performance liquid chromatography was detected in crude extracts of maize (Zea mays) coleoptiles. The product was identified as IAA by mass spectrometry. The IAA-forming activity was co-purified with an indole-3-acetaldehyde (IAAld) oxidase activity by chromatography on hydrophobic and gel filtration (GPC-100) columns. During purification, the IAA-forming activity, rather than that of IAAld oxidase, decreased; but when hemoprotein obtained from the same tissue was added, activity recovered to the same level as that of IAAld oxidase. The promotive activity of the hemoprotein was confirmed by the result that the activity coincided with amounts of the hemoprotein after GPC-100 column chromatography. The hemoprotein was characterized and identified as a cytosolic ascorbate peroxidase (T. Koshiba [1993] Plant Cell Physiol [in press]). The reaction of the IAA-forming activity was apparently one step from tryptophan. The activity was inhibited by 2-mercaptoethanol. The optimum temperature for the IAA-forming system as well as for the IAAld oxidase was 50 to 60[deg]C, and the acitivity at 30[deg]C was one-third to one-half of that at 60[deg]C. The system did not discriminate the L- and D-enantiomers of tryptophan.

Novel synthesis of hexaaryl[3]radialenes via dibromo[3]dendralenes

Abstract We report here an efficient route to the synthesis of highly fluorescent hexaaryl[3]radialenes using the oligomerization of ate-type copper carbenoids, followed by cyclization with hexamethylditin and Pd(PPh3)4; the structures of the [3]dendralene and hexaaryl[3]radialenes were determined by X-ray crystallographic analysis.

Synthesis of benzocyclobutadiene trimers and all-Z-tribenzo[12]annulene. A new family of concave π-systems

Abstract Nickel-catalyzed oligomerization of trans-1,2-dibromobenzocyclobutene formed cyclic dimers and trimers. Upon heating, the major anti-cyclic trimer afforded a cage compound, whereas the minor syn-trimer produced all-Z-tribenzo[12]annulene. Dehydrogenation of the anti-trimer with DDQ resulted in the formation of an indenoazulene derivative, and a similar reaction of the syn-trimer yielded a bowl-shaped system. All-Z-tribenzo[12]annulene was also synthesized using a stepwise route starting from o-diiodobenzene and o-ethynylbenzyl alcohol, the overall yield being 22%. All-Z-tribenzo[12]annulene behaved like π-prismand and formed chromium(0) tricarbonyl and silver(I) complexes.

Copper(I), silver(I), and gold(I) complexes of all-Z-tribenzo[12]annulene

Abstract The copper(I) and silver(I) complexes of all-Z-tribenzo[12]annulene were synthesized and the structures were determined by X-ray analysis. The trigonal olefinic cavity of the [12]annulene incorporates copper and silver cations to produce stable complexes, whereas the gold(I) complex was unstable, yielding a cyclization product via isomerization of the Z-double bonds.

[6.6](1,8)Naphthalenophane containing 2,2′-bithienyl-5,5′-ylene bridges☆

Two isomeric 1,8-[1,8-naphthylenebis(2,2′-bithienyl-5,5′-ylene)]naphthalenes (major and minor isomers) were synthesized using the coupling reaction of 1,8-di(5-lithio-2-thienyl)naphthalene with CuCl2. The major isomer easily isomerized photochemically to yield the minor isomer. The redox and fluorescence behavior of the two isomers reflect both face-to-face interaction of the 2,2′-bithienyl-5,5′-ylene units and deformation of the naphthalene moieties.

Phase transition in crystalline p-polyphenyls : heat capacity of 4,4'''-difluoro-p-quaterphenyl

Abstract The heat capacity of crystalline 4,4‴-difluoro- p -quaterphenyl was measured from 8 K to 303 K by adiabatic calorimetry. A broad anomaly was detected between 140 and 250 K and attributed to a structural phase transition associated with molecular twisting. The temperature, the enthalpy and the entropy of transition were determined as (200.5 ± 0.5) K, (322 ± 20) J·mol −1 and (1.65 ± 0.10) J·K −1 ·mol −1 , respectively. The properties of the transition are compared with those of unsubstituted and fluorine-substituted p -polyphenyls (of two to four benzene rings in a molecule) in the light of a unified model of displacive and order-disorder types of structural phase transition.

An efficient synthesis of (R)-(+)-recifeiolide and related macrolides by using enantiomerically pure (R)-(−)-5-methyl-2,2,2-triphenyl-1,2λ5-oxaphospholane

Abstract E-(R)-(+)-8-Dodece-11-olide, which is known as recifeiolide, was synthesized by a six-step reaction starting from (R)-(+)-propene oxide in a total yield of 53 %. The key step of this synthesis is the preparation of (R)-(−)-methyl 11-hydroxy-8-dodecenate using (R)-(−)-5-methyl-2,2,2-triphenyl-1,2λ5-oxaphospholane. Be using this method, enantiomerically pure 13- and 14-membered macrolides were also synthesized.

Charge-transfer complex and radical cation salt of a new donor EDT-TTFCL2: unique conductivities and crystal structures

X-Ray structural analyses of the charge-transfer complex (EDT–TTFC12)2·TCNQF4, 2, and the radical cation salt EDT–TTFC12·ClO4, 3, revealed an interesting effect of chlorine substitution on the crystal stacking mode; the electrical conductivity of 2 is unusually high, although it has a mixed-stacking structure.

Synthesis and stereochemistry of an optically active selenonium ylide. X-Ray molecular structure of (+)Se-{4′-[(–)-menthyloxycarbonyl]phenyl}(methyl)-selenonium 4,4-dimethyl-2,6-dioxocyclohexylide

Fractional recrystallization of diastereoisomeric {4′-[(–)-menthyloxycarbonyl]phenyl}(methyl)-selenonium 4,4-dimethyl-2,6-dioxocyclohexylide from hexane–diethyl ether gave the optically pure (+)-selenonium ylide as stable crystals. The absolute configuration around the selenium atom was determined to be R by X-ray crystallographic analysis. The epimerization of the optically active selenonium ylide by pyramidal inversion was studied.