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Hg(OTf)2-catalyzed aryl–allene cyclization accompanied by formation of a quaternary carbon center has been realized. Deuterium-labeling experiments and computational modeling were used to propose a novel catalytic pathway involving direct H-transfer from the aromatic ring to the vinyl mercury moiety followed by mercury 1,2-migration.

A method for the facile synthesis of ethene-bridged terthiophenes (EBTTs) in two steps has been developed. The first step is a double Sonogashira coupling between 3′,4′-dibromo-2,2′:5′,2″-terthiophene and terminal alkynes to give dialkynylated terthiophenes, and the second step is a cyclization reaction to afford EBTTs. The fundamental physical properties of EBTTs were also studied.

In the presence of 1.5 equivalents of H2SO4, vinylazetidines are found to undergo ring expansion to benzazocine derivatives like (II) which are unstable undergoing ring contraction to vinyltetrahydroquinolines (III) under slightly acidic conditions.

A novel electrophilic-type trifluoromethylthiolation reagent, a trifluoromethanesulfonyl hypervalent iodonium ylide, was designed and reacted well with various nucleophiles to afford the desired CF3S-substituted products. In situ reduction of the trifluoromethanesulfonyl group to give the trifluoromethylthio group, which is the key step in this process, was realized in the presence of copper(I) chloride.

The Ni-catalyzed cycloaddition of substrates (I) and (VII) provides bicyclic systems which consist of oxazine and nine-membered ring moieties.

Newly synthesized ortho-functionalized spirobiindane-based catalysts are used for the asymmetric title reaction.

The cycloaddition reaction of 2-vinylazetidines with benzyne proceeded smoothly without a catalyst, and various benzazocine derivatives were isolated in good to high yields. The scope of the reaction, as well as the reactions of other arynes, has been studied.

The title compounds are synthesized from the elements using excess Cu and Si, Ge, or Sn as a flux (alumina crucibles, 1100 °C, 2 h).

The title salt efficiently promotes the formation of pyrrolidine, piperidine, indole, quinoline, isoquinoline, and tetrahydronaphthalene derivatives.

The selective monoallylation of 1,2-diols occurs in the presence of a new bimetallic Pd/Sn catalyst system containing 1,4-bis(diphenylphosphino)butane as ligand.

Treatment of 2-vinylaziridines of type (I) and (VI) with sulfonyl isocyanates in CH2Cl2 allows a new and simple access to 7-membered cyclic ureas.

The Ru complexes (I) are found to be highly efficient catalysts for the asymmetric hydrocyanation of aromatic, α,β-unsaturated, and tert-alkyl aldehydes.

Condensation of dihydrofuran- and -thiophenecarbonitriles (I) and (V) possessing an active methylene group with N,N-dimethylformamide dimethyl acetal (II) results in the formation of enamines (III) and (VI).

Coupling of the haloboron subphthalocyanine (I) with Grignard reagents affords title compounds of type (III) bearing an axial substituent at the boron—carbon direct bond.

The ring expansion reaction of ethyl cyclopropylideneacetate (1) with benzosilacyclobutenes proceeded smoothly in the presence of Ni(cod)2-TOPP (tribiphenyl-2-yl phosphite) to give benzosilacycloheptenes in good yields. This formal σ bond metathesis reaction proceeded in a selective manner. The Ni-catalyzed reaction of 1 with biphenylenes was also examined.

Novel tricyclic ring systems, irmdazo[3,4-d]pyridazino[4,5-b][1,4]thiazines 3, imidazo[2,1-b]pyridazino[4,5-e][1,3,4]thiadiazines 15 and 18 were prepared by the reaction of 5-amino-4-chloropyridazin-3(2H)-ones 1 and 5(4)-(1-methylhydrazino)-4(5)-chloropyridazin-3(2H)-ones 13 (16) with isothiocyanates 2 and 7.

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

Terminal N-monoacylated triamines 6 were easily obtained by hydrolysis of the acylated fused piperazines 5, which were prepared by the reaction of triamines 1 with benzil 2 followed by acylation.

Chlorocarbonylsulfenyl chloride was allowed to react with 1-alkylidene-4-phenylthiosemicarbazones in the presence of triethylamine to give 1,2,4-triazolines, whereas with 1-arylidene-4-phenylthiosemicarbazones to afford 1,2,4-dithiazolidines. Treatment of diarylidenethiocarbohydrazides and diarylidenaminoguanidines with chlorocarbonylsulfenyl chloride under similar conditions gave 1,2,4-dithiazolidines and 1,2,4-thiadiazolidines, respectively.

5-Hydrazinopyridazin-3(2H)-ones 1 reacted with dimethyl acetylenedicarboxylate 2 to give 4,6-dihydropyridazino[4,5-c] pyridazin-5-(1H)-ones 3 by cyclization with dehydrogenation. On the other hand, the reaction of 4-bromo-5-hydrazino- and 5-bromo-4-hydrazinopyridazin-3(2H)-ones 8 and 10 with diester 2 resulted in the novel cyclization with rearrangement to give compounds 3 and 9 together with the expected cyclization products.

Substituted thiosemicarbazones were allowed to react with α-chloroacetyl chloride to give two types of 1,3-thiazolin-4- ones which arose from the different cyclization depending on the substituents

Enantiodifferentiating cis-trans photoisomerization of 1,2-diphenylcyclopropane (1) in the presence of (−)-tetramenthyl 1,2,4,5-benzenetetracarboxylate as a chiral sensitizer gave (+)-(1S,2S)-1t in enantiomeric excesses (e.e.) of 10.4 and 2.8% in pentane and acetonitrile, respectively, while the photosensitization with the corresponding (−)-tetrabornyl ester afforded (+)-(1S,2S)-1t (3.8% e.e.) in pentane and, notably, the antipode (−)-(1R,2R)-1t (2.4% e.e.) in acetonitrile.

The reaction of 5-hydrazinopyridazin-3(2H)-ones 1 with α-keto diester 2 in acetic acid afforded the corresponding 4,6-dihydropyridazino[4,5-c]pyridazin-5(1H)-ones 3 and pyrrolo[2,3-d)pyridazin-4(5H)-ones 4. Compounds 3 were also obtained from 4-bromo-5-hydrazinopyridazin-3(2H)-ones 8 and 2 under milder conditions. 5-Bromo-4-hydrazinopyridazin-3(2H)-one 9, the regioisomer of 8b, also reacted readily with 2a to give 4,7-dihydropyridazino[4,5-c]pyridazin-8(1H)-one 10b, the regioisomer of 3b.

Cyclization of the Michael adducts 1 and 6 formed from ene-hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of polyphosphoric acid (PPA) produced the fused 1,2-diazepine rings 2 and 7. However, the adducts when heated in 1,2,3,4-tetrahydronaphthalene (tetralin) preferentially provided the fused pyridone rings 4 and 10 and the fused pyrrole rings 5 and 11.

Photosensitized cycloaddition of 4,6-dimethyl-2-pyrone (1) with methacrylonitrile (3b) afforded two types of [2+2]cycloadducts, oxabicyclo[4.2.0]octenes 4b and 6b, across the C 5 -C 6 and C 3 -C 4 double bonds in 1, respectively. Photosensitized reactions of 1 with dimethyl maleate and dimethyl cyclobutene-1,2-dicarboxylate gave [2+2]cycloadducts oxabicyclo[4.2.0]octenes 4d, oxatricyclo[4.4.0.0 7 ,10]decene 4e across the C 5 -C 6 double bond, in addition to [2+2]cycloadduct oxabicyclo[2.2.2]octene 9d or bicyclo[4.2.0]octadiene 10e. The photoreactions of methyl 2-pyrone-5-carboxylate (2) with 3b and 2-chloroacrylonitrile (3c) gave [2+2]cycloadducts oxabicyclo[2.2.2]octene 5b, 5c in addition to [2+2]cycloadducts oxabicyclo[4.2.0]octenes 11b and 11c across the C 5 -C 6 double bond in 2. The ptotocycloaddition mechanism was explained from results calculated by means of PM3-CI method. Namely, the site- and:or regio-selectivite products, 4,5,8,9 and 10 were thought to come from the same site-selective radical intermediates in the case of electron-poor olefins.

In an effort to generate photoproducts with higher optical purities (op), two novel strategies, i.e., intra/intermolecular triplex formation and increased steric hindrance, have been employed in the enantiodifferentiating Z→E photoisomerization of cyclooctene (1) sensitivity by optically active (ar)alkyl bezene(poly)carborylates 2-5 at temperatures ranging from 25 to -90 o C

Two platelet activating factors (PAF) were conveniently prepared from optically active epichlorohydrin via 5 steps in 15–16% total yield. Four analogues containing oleoyl, propyl, p-trifluoromethylphenoxy, and N,N-dimethyldithiocarbamoyl groups were also prepared.

A variety of fervenulin type products, 3-substituted 8-phenylpyrimido [5,4-e]-1,2,4-triazine-5,7(6H,8H)-diones (18a-i), were synthesized by nitrosative or nitrative cyclization of the aldehyde hydrazones (17a-i) derived from 6-(1-methylhydrazino)-1-phenyluracil (16) with aliphatic as well as aromatic aldehydes. The compound (16) was prepared by the reaction of 6-chloro-1-phenyluracil (8) with methylhydrazine. In addi- tion, not only the precursor of (16), 6-chloro-1-phenyluracil (8), but also other new chlorinated regioisomers of mono N-substituted pyrimidine (9) and uracil (14) were isolated and characterized by the reductive dechlorination of them

6-Phenyl analogs of toxoflavin (1-methyl-6-phenylpyrimido[5,4-e]-1,2,4-triazine-5,7(1H,6H)-diones ) (7a--f) and their 4-oxides (8a-f) were synthesized by nitrosative or nitrative cyclization of the aldehyde hydrazones (6a-f) of 6-(1-methylhydrazino)-3-phenyluracil (5). Both sets of compounds, 7a-f and 8a-f, gave the corresponding 1-demethyl derivatives (10a-f) upon treatment with nucleophiles such as dimethylformamide (DMF) and acetic acid under heating. The activities of toxoflavins (1a-e), toxoflavin 4-oxides (3a-e) and their 6-phenyl analogs (7a-f and 8a-f) against a variety of bacterial and fungal strains were examined. Most of the compounds showed strong inhibitory activities against gram-positive bacteria. Among the compounds, 1c, 1d, 1e, and 3c exhibited the strongest inhibitions of Micrococcus lutea (0.5 micrograms/ml minimal growth-inhibitory concentration) and Staphylococcus aureus 4R (1 microgram/ml), as well as Bacillus subtilis and Staphylococcus aureus (1-2 micrograms/ml). Most of the compounds had strong antifungal activity (2-100 micrograms/ml minimal growth-inhibitory concentration) against Candida albicans and Saccharomyces cerevisiae.

Effective Michael addition of α-chloro ketones to αβ-unsaturated ketones was performed under mild conditions promoted by N-stannylcarbamate. Cyclopropane derivatives were obtained stereoselectively.

A novel macrocyclic spermidine alkaloid, albizzine A has been isolated from bark of Albizzia myriophylla. The structure was established on the basis of spectral evidence.

1,3 : 2,4-Di-O-benzylidene-D-sorbitol (D-DBS) can cause gelation of organic solvents of a wide range of polarity into a gel state. The aggregated structures of D-DBS/organic solvent systems were studied, mainly by using IR, UV, and circular dichroism (CD) spectroscopy. In the case of the racemate DL-DBS, no gel state was formed. In IR spectra of D-DBS and DL-DBS in the solid state, the intensities of νOH and νCO absorption in D-DBS were found to be larger than those in DL-DBS. It is assumed that the hydrogen bonding formed between an acetal oxygen and a hydroxyl group in the aggregation of D-DBS. From the changes in the IR spectra from solution into a gel state, we can conclude that the chirality and the hydrogen bonding of DBS molecules are essential for the formation of the gel. Comparing the gel-forming ability of D-DBS with its derivatives, 5- or 6-hydroxyl-group-blocked compounds by methyl group, the 6-hydroxyl group seems to be important in the formation of D-DBS aggregates. The results of UV spectr...

In a search for inhibitors of gastric H+/K+ATPase, 4-(phenylamino)quinoline-3-carboxamides were synthesized and evaluated for antisecretory activity against histamine-induced gastric acid secretion in rats. These compounds were synthesized by condensation of aniline derivatives with N-substituted 4-chloroquinoline-3-carboxamides, which were obtained from treatment of 4(1H)-quinolinone-3-carboxylic acid with thionyl chloride. Most of the compounds inhibited histamine-induced gastric acid secretion in rats. Among them, N-allyl-4-(2-ethylphenylamino)quinoline-3-carboxamide (4h) was the most potent inhibitor and had the best profile as a candidate antiulcer agent. This compound showed reversible, K+-competitive gastric H+/K+-ATPase inhibitory activity.

Triflates of 2-hydroxymethytene t-butyl esters, derived from simple t-butyl esters, were treated with potassium t-butoxide in THF to generate alkylidenecarbenes. At room temperature, they underwent intramolecular 1,5 C-H insertion giving t-butyl cyclopentenecarboxylates.