Teruo Matsuura

A novel two-phase oxidative coupling of 2-naphthols suspended in aqueous Fe3+ solutions

Abstract The oxidative coupling of 2-naphthols suspended in aqueous Fe3+ solutions gives corresponding 1,1′ -bi-2-naphthols in the yields of 91–95%. This reaction can be also effectively applied to the large-scale synthesis of 1,1′ -bi-2-naphthol. It was suggested that the oxidation occurred at the surface of the crystalline 2-naphthols via a solid-liquid process.

Preparation, structure and discrimination of a chiral bimolecular crystal by the self-assembly of 3-indolepropionic acid and phenanthridine

Although 3-indolepropionic acid and phenanthridine are achiral molecules, a chiral bimolecular crystal is spontaneously formed; torsional conformation of the propionic acid group plays an important role in the helix formation through hydrogen bonding chain within the crystal lattice.

Ionic chiral handle-induced asymmetric synthesis in a solid state Norrish type II photoreaction

Abstract Irradiation of crystals of salts formed between 4-(2,4,6-triisopropylbenzoyl)benzoic acid ( 1a ) and various optically active amines is shown to lead to optically active Norrish type II photoproducts in low to moderate enantiomeric excesses, a process in which the ammonium ion has acted as an “ionic chiral handle.” X-ray crystallography reveals that the salts crystallize with two independent, mirror image-related molecules of the benzophenone moiety in the asymmetric unit, and this is suggested to be the source of the low ee s observed.

Organic chemical approach to photo-crosslinks of nucleic acids to proteins

Various proteins are known to be linked covalently to nucleic acids under UV irradiation. The phOto-cross-links occurs from the interacting states between nucleic acids and proteins. The present approach to this problem involves the characterization and identification of photoproducts obtained from model systems using simple pyrimidine bases and amino acids as well as some mechanistic aspects. 5-Bromouracil or its derivatives undergoes selective photocoupling to tryptophan, indoles and some electron-rich aromatics under varthus irradiation conditions, where four modes of reactions were observed: involvement of (1) triplet bromouracil, (2) a double electron transfer in the presence of an electron carrier, (3) mixed aggregate formation in aqueous frozen solution, and (4) fluorescence quenching of the aromatics by bromouracfl. Other topics of the photochemistry of pyrimidine bases, including synthesis of fluorescent uracils using photo-cross-coupling with 5-chloroand 5-iodouracils, photoreactions between a 4-thiouracil and L—lysine and between thymine and L-tryptophan, and synthesis and behaviors of model compounds for stacking interactions between 5-bromouracil (or thymine) and tryptophan.

SOLID‐STATE PHOTOCHEMISTRY OF INDOLES WITH NAPTHALENE AND PHENANTHRENE

Abstract— Solid‐state irradiation of mixed crystals prepared by meltinga 1:3 molar mixture of indole and phenanthrene followed by resolidifying the melt gave an adduct 2a in 13.5% yield. An adduct 2b was obtained by irradiation of the mixed crystals of 3‐methylindole and phenanthrene. Irradiation of the same mixtures of indoles and phenanthrene in solution gave no photoproduct. Irradiation of the mixed crystals of indole and naphthalene gave a similar photoadduct 3a, which was also formed in solution. The 1:1 mixed crystals of indole and phenanthrene and of indole and naphthalene were characterized by various spectroscopic methods. Among them powder X‐ray diffraction spectral analysis and differential scanning calorimetry revealed that the former mixed crystal is a simple mixture of microcrystals of indole and phenanthrene, while the latter forms a molecular compound.

Base-catalysed oxygenolysis of 3-hydroxyflavones

3-Hydroxyflavones, except those containing a 7-hydroxy-group, undergo base-catalysed oxygenolysis under mild conditions leading to oxidative cleavage of the heterocyclic ring to give the corresponding depsides and carbon monoxide in excellent yields. The same result is obtained in the reaction of quercetinase, a dioxygenase. The oxygenation of 3,4′,7-trihydroxyflavone in aqueous solution gave p-hydroxyphenylglyoxylic acid and 2,4-dihydroxybenzoic acid; in absolute methanol containing sodium methoxide methyl 4-hydroxyphenylglyoxylate and methyl 2,4-dihydroxybenzoate as well as 4-hydroxyphenylglyoxylic acid were obtained. The formation of these products is rationalized by assuming that 2-hydroperoxy-4′,7-dihydroxyflavan-3,4-dione is formed first and is reduced with the intervention of the 7-hydroxy-group to give 2,4′,7-trihydroxyflavan-3,4-dione, which is solvated and oxidized under the reaction conditions. 2′-Substituted-3-hydroxyflavones were not susceptible to oxygenolysis.

Two-Molecule Crystals Between Nitroanilines and Nitrophenols

Abstract Slow evaporation of a 1: 1 or 1: 2 molar solution of p-nit roaniline and p-nitrophenol in a mixture of dichloromethane and n-hexane deposited two kinds of single crystals which were mechanically separated: 2: 1 molecular crystal A and 1: 3 molecular crystal B. In a similar manner a 1: 1 or 2: 1 molar solution of m-nitroaniline and m-nitrophenol in a mixture of chloroform and petroleum ether deposited the single crystals of 2 : 1 molecular crystal C. The crystal structures of A, B and C were found to be isomorphic to those of p-nitroaniline, p-nitrophenol (b form) and m-nitroaniline, respectively. The characteristics of the crystal structures of A, B and C are discussed.

Chirality memory controlled by the crystal lattice of a molecular compound

Abstract Irradiation of crystalline charge transfer complex 3 formed between (S)-(+)-2-(6-methoxy-2-naphthyl)propanoic acid 1 and 1,2,4,5-tetracyanobenzene 2 is shown to lead to the optically active decarboxylated-coupled product (+)-4 in high yield and substantial enantiomeric excess. In this process the configuration of the stereogenic carbon in 1 is retained to some extent by the control of the crystal lattice. The factors which affect the reaction of the molecular crystals were also examined. The relationship between the reactivity and the crystal structure is discussed.

Solid-state photochemistry of the mixed crystals between benzoquinones and polymethylbenzenes

Abstract Nine mixed crystals combined 1,4-benzoquinone (1), 2,5-xyloquinone (2) and duroquinone (3) with durene (a), pentamethylbenzene (b) and hexamethylbezene (c) were prepared by a melting-resolidifying process and characterized by powder X-ray diffractometry, DSC and IR. Only the mixed crystal of 3 and a formed a 2:1 novel molecular crystal (4); other eight mixed crystals were simple polycrystalline mixtures of the two components. Irradiation of the molecular crystal 4 (3/a) and the mixed crystals 1/a, 1/b and 3/b caused intermolecular hydrogen abstraction to give hydroquinones and in some cases adducts. Product selectivities in the solid state were different from those in solution. Correlation between the crystal structure and the reactivity of 4 is discussed.

Base-catalysed autoxidation of 3,4′-dihydroxyflavone

Autoxidation of 3,4′-dihydroxyflavone in dimethylformamide in the presence of potassium t-butoxide results in oxidative cleavage of the hetrocyclic ring to give 2-(4-hydroxybenzoyloxy) benzoic acid and carbon monoxide in excellent yields; this provides a nonenzymic model for the reaction of quercetinas.