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It is found that the retention of the configuration of the hydroxyl group as a leaving group bases on the conformational stability of the carbocation intermediate supported by a flexible silyl substituent.

A novel one-step synthesis of enantioenriched 1,4-oxazepan-7-ones is achieved by cyclization of optically active alkynyl esters in the presence of Ph3PAuCl and Cu(OTf)2 as the catalysts.

Carbon–carbon bonds were formed between tertiary amines and carbon nucleophiles such as nitroalkanes, ketones, trimethylsilyl cyanide, or indole under aerobic photooxidative conditions by using 2-chloroanthra-9,10-quinone as an organocatalyst. This reaction uses harmless visible-light irradiation with molecular oxygen as the terminal oxidant.

The monomeric α-Dawson-type [B-α-H3P2W15O59{Al (OH2)}3]6- polyoxoanion of (IV) having an overall C3v symmetry is obtained under acidic conditions while a H-bonded dimeric [B-α-H3P2W15O59{Al (OH)}2{Al(OH2)}]216- anion with an overall S3 symmetry is obtained under basic conditions.

The best results are obtained when the irradiation is carried out with only one lamp instead of four lamps.

Photochemical treatment of enyne compounds of type (I) with large excess of disulfide results in convenient and stereoselective formation of pyrrolothiophene derivatives which are of biological interest.

Treatment of mesoionic 1,3-oxazolium-5-olates with TosMIC in the presence of a base causes a novel ring transformation affording 2(1H)-pyrazinones in moderate yields. The origin of C-2 carbonyl oxygen in the product was elucidated to be molecular oxygen, based on 18O-labeling experiments.

Dihydrostannolanes (I), readily available by a radical cascade reaction, undergo a novel double Migita-Kosugi-Stille coupling reaction with dihalobenzenes in the presence of a palladium catalyst.

Title compounds (III), (V), and (VII) are prepared using Sonogashira—Hagihara conditions and show the small HOMO-LUMO energy gaps due to their effective π-conjugation.

The photooxidative oxylactonization of 4-acylbutyric acids proceeds readily in perfluorohexane in the presence of TFAA as a promoter.

The radical cyclization of chiral aza-Morita—Baylis—Hillman adducts (I) with Bu3SnH yields bicyclic stannolanes (III) with high diastereoselectivity.

6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics.

The NHC-catalyzed thioesterification of aromatic or aliphatic aldehydes with a range of thiols was developed in the presence of a stoichiometric amount of an organic oxidant. Among the oxidants examined, phenazine was shown to give the best results in terms of chemical yield and compatibility with thiols.

Hydrogen-bond (HB)-donor catalysts that bear a 2-aminoquinazolin-4-(1H)-one or a 3-aminobenzothiadiazine-1,1-dioxide skeleton have been developed, and it has been shown that these catalyst motifs act similarly to other HB-donor catalysts such as thioureas. The highly enantioselective hydrazination of 1,3-dicarbonyl compounds was realized even at room temperature with up to 96% ee for 2-aminoquinazolin-4-(1H)-one-type catalysts, which were more effective than the corresponding urea and thiourea catalysts. In addition, benzothiadiazine-1,1-dioxide-type catalysts were shown to promote the isomerization of alkynoates to allenoates with high enantioselectivity. To overcome the problem that the products were obtained as mixtures with the starting alkynoates, we developed the tandem isomerization and cycloaddition of alkynoates for the synthesis of advanced chiral compounds such as bicyclo[2.2.1]heptenes and 3-alkylidene pyrrolidine without a significant loss of enantioselectivity.

Novel bisimide-fused acenes were synthesized viabismuth triflate mediated double-cyclization reaction of acid chlorides and isocyanates. Their optical and electrical properties revealed significantly smaller HOMO–LUMO gaps compared with those of their parent acenes. Fabricated OFET based on tetracene bisimide showed n-type OFET outputs.

A new mild and economic deprotection method for 2,2,2-trichloroethoxycarbonyl-protected amines in the presence of Tms-Cl-activated mischmetal is presented.

Treatment of 4-perfluoroalkyl-4-hydroxy-2,5-hexadien-1-one (4-perfluoroalkyl-4-quinol), prepared from the reaction of 1,4-benzoquinone with perfluoroalkyllithium, with acetic anhydride–sulfuric acid gave a mixture of 2,4-diacetoxy-1-perfluoroalkylbenzene and 1,2-diacetoxy-4-perfluoroalkylbenzene in a comparable ratio. When 4-perfluoroalkyl-4-quinols bearing a methyl group ortho to the perfluoroalkyl group were subjected to the rearrangement, acetoxymethyl compounds were obtained in addition to diacetoxybenzene derivatives. Only 1,3-migration was observed in the cases of 2,4-di-t-butyl-4-perfluorooctyl-4-quinol and 4-hydroxy-4-perfluoroalkyl-1(4H)-naphthalenone, while the reaction of 2,6-dimethyl and 2-methoxy derivatives gave only 1,2-shift products. Reaction routes to the apparent 1,2- and 1,3-acetoxyl migration products are discussed.

The reactions of amidinothioureas, imidoylthioureas, thioacylamidines, O-methyl-1-aryl-2-thioisobiurets, and 1-aryl-isodithiobiurets with diethyl azodicarboxylate (DEAD, diethyl diazenedicarboxylate) gave the corresponding thiadiazoles by the oxidative cyclic S−N bond formation. Analogously, the oxidative cyclization of 2-phenyl-5-(1-methylthiosemicarbazido)-3(2H)-pyridazinones with DEAD provided 4-methyl-7-phenyl-4H-pyridazino[4,5-e][1,3,4]thiadiazin-8(7H)-ones

In the presence of cyclodextrins (CDs), the ring-opening reaction of styrene oxide with NaBH4 in aqueous media proceeded smoothly to give 1-phenylethanol with high selectivity of up to 94%, and kinetic resolution of the racemic epoxide was observed. Kinetic studies suggest the resolution based on the different reaction rates between two enantiomers included in the CD’s cavity. The reaction of epoxides such as 1,2-epoxyindan and 1,2-epoxy-3-phenylpropane are also affected by the addition of CDs to proceed smoothly with high regioselectivities.

1-Substituted 1,2-dihydroisoquinolines, derived from isoquinoline and organolithium reagents, readily undergo autoxidation to lead to 4-isoquinolinols in moderate yields.

2-Aryl-1-chloro-1-fluoroethyl sulfoxides underwent nucleophilic desulfinylation with PhMgBr to give (Z)-fluorostyrene derivatives in a very stereoselective manner (> 33 : 1) via an α-fluorocarbene species. When treated with 3 equiv of PhLi in the presence of N,N,N′,N′-tetramethylethylenediamine, they similarly formed fluorostyrenes as a stereoisomeric mixture (E : Z = 2 : 1), but with 1 equiv of PhLi 2-aryl-1-chloro-1-fluoroethanes were the major product. On the other hand, no formation of a fluoroalkene was observed in the desulfinylation of 1-chloro-1-fluoro-4-phenylbutyl sulfoxide with the nucleophiles. In the latter reaction, oxidation and/or phenylation of the intermediate carbene were the main pathways.

Treatment of 2-(4-biphenylyl)-2-t-butyldimethylsilyloxy-1-chloro-1-fluoroethyl phenyl sulfoxide with PhMgBr resulted in the formation of a fluorostilbene derivative, a fluoro enol silyl ether and small amounts of 4-(fluoroacetyl)biphenyl, while a similar reaction of 2-methoxymethoxy analog mainly led to the fluorostilbene derivatives and a simple desulfinylation product. In contrast, both sulfoxides reacted with PhLi to give chlorofluoro compounds and fluoro enol ethers. In these reactions, the stability of carbenoids derived from the nucleophilic removal of the sulfoxide moiety was greatly affected by the β-substituents, thus controlling the product distributions.

In the presence of boron trifluoride, perfluoroalkyllithiums generated in situ from tbe reaction of n-perfluoroalkyl iodides with methyllithium-lithium bromide smoothly added to a carbon-nitrogen double bond of bicyclic azaarenes and diazines to give the corresponding perfluoroalkylated dihydro heterocycles, which often underwent spontaneous aromatization in air. Perfluoroalkylation occurred preferentially at the carbon next to nitrogen in azaarenes even when the carbon atom was occupied by an alkyl substituent. Only one exception observed was the reaction of acridine where a perfluoroalkyl group was introduced at 9 position.

Glass-ceramics containing barium–mica in the system Ba0.5 Mg3 (Si3AIO10)F2–2MgO · 2Al2O3· 5SiO2–Ca3 (PO4)2 are two to three times stronger than conventional mica-containing glass-ceramics. Moreover, the barium-mica glass-ceramics are easier to machine, as confirmed by a drilling test using conventional steel tools. Such mechanical properties are attributable to the microstructure of the barium–mica glass-ceramics. Very fine, interlocking mica crystals are precipitated in the glass, and a crack-deflection mechanism is observed by scanning electron microscopy.

Treatment of 4-perfluoroalkyl-4-quinols with a catalytic amount of potassium t-butoxide gave 2-(perfluoroalkyl)hydroquinones or 5-perfluoroalkyl-2-cyclohexene-1,4-diones in good to moderate yields depending upon the substitution pattern of the quinols. Similarly, 2-hydroxy-3-methyl-2-perfluorooctyl-1-propyl-3-pyrrolin-5-one underwent the base-induced rearrangement to afford a perfluoroalkylated succinimide derivative.

Several reactions of 6,6a,7,8,9,10,10a,11-octahydro-11-oxodibenzo[b,e]thiepins and -oxepins were studied, which included reduction, oxidation, the Grignard reaction, thiation, and the Wittig reaction. Stereochemistry of the reaction products was confirmed on the basis of proton nuclear magnetic resonance analysis

In the presence of BF 3 -OEt 2 , (perfluoroalkyl)lithiums generated in situ from the reaction of primary perfluoroalkyl iodides and MeLi-LiBr reacted with imines, azines, and nitrones to afford perfluoroalkylated nitrogen-containing compounds in moderate to good yields. This method was successfully applied to the preparation of a (perfluoroalkyl)glycine and optically active perfluoroalkylated amines

Heating a DMSO solution of 4-(perfluoro-n-alkyl)-4-hydroxy-2,5-cyclohexadien-1-one (4-perfluoroalkyl-4-quinols) in the presence of a catalytic amount of base brought about 1,2-migration of the perfluoroalkyl group to give 2-(perfluoro-n-alkyl)hydroquinone or 5-(perfluoro-n-alkyl)-2-cyclohexene-1,4-dione depending upon the substitution pattern of the quinol. The similar rearrangement of 4-perfluoroisopropyl-4-hydroxy-2,5-cyclohexadien-1-one occurred very smoothly at room temperature under the basic conditions. 5-Hydroxy-4-methyl-5-perfluorooctyl-1-propyl-3-pyrrolin-2-one underwent the base-induced rearrangement to afford a perfluorooctylated succinimide derivative. On the other hand, 5-hydroxy-3-methyl-5-perfluorooctyl-1-propyl-3-pyrrolin-2-one and 5-hydroxy-1-isobutyl-5-perfluorooctyl-3-pyrrolin-2-one did not suffer any rearrangement, although their structures were very similar to the 4-methylated one.

High-strength bioactive ceramics, MgO-CaO-SiO 2 -P 2 O 5 glass-ceramic composites toughened by zirconia, were prepared by sinter-hot isostatic pressing (sinter-HIPing) to achieve easier mass production and higher reliability. Raw materials for preparing a dense presintered body were investigated to obtain almost complete densification by sinter-HIPing. It was found that the densification of a presintered body was influenced by residual glassy phases in the crystallized glass particles. By using a controlled crystallized glass powder and a zirconia powder as raw materials, a presintered body with a relative density higher than 94% was prepared, and then it was densified to near its theoretical density by sinter HIPing. This bioceramic exhibited an extremely high bending strength of 400 to 1000 MPa and fracture toughness of 3 to 5 MPa.m 1/2 for 30 to 80 vol% of zirconia

The acid-base properties of the ZnBr2-NaBr melts at 623 K were investigated on the basis of the electromotive force measurements of a zinc-zinc concentration cell. The following two chemical equilibria were postulated to describe the acid-base character of the melts.

(1 R ,2 R ,6 S ,7 S )-5-Aza-1,10,10-trimethyl-3-oxatricyclo[5.2.1.0 2,6 ]decan-4-one ( endo -oxazolidinone) and (1 R ,2 S ,6 R ,7 S )-isomer ( exo -oxazolidinone) are found to be efficient diastereomeric auxiliaries for Diels-Alder reactions, which are promoted by Lewis acid catalysts with predictable absolute stereochemistry. Thus, the reaction of cyclopentadiene with N -crotonyl-or N -cinnamoyl- endo -oxazolidinones gave (1 R ,2 R ,3 S .4 S )-3-methyl- or (1 R ,2 S ,3 S ,4 S )-3-phenylbicylo[2.2.1]hept-5-ene-2-carboxylates, while their enantiomers, i.e. (1 S ,2 S ,3 R ,4 R )-3-methyl- or (1 S ,2 R ,3 R ,4 R )-3-phenylbicyclo[2.2.1]hept-5-ene-2-carboxylates were obtained stereoselectively from the corresponding exo -oxazolidinone derivatives.