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Seven novel limonoids, e.g. mexicanolide-type carapanolides R (Ia) and S (Ib) are isolated from the oil of Carapa guianensis.

The catalytic and asymmetric cycloaddition between 3-[1-(silyloxy)vinyl]indoles and electron-deficient olefins gave substituted hydrocarbazoles in up to 99% yield and 94% ee. This reaction was catalyzed by a novel chiral holmium(III) complex. Alkylation of the cycloadduct gave a tricyclic compound with four continuous chiral centers, one of which was a quaternary carbon.

The sequential addition of aromatic Grignard reagents to O-alkyl thioformates proceeded to completion within 30 s to give aryl benzylic sulfanes in good yields. This reaction may begin with the nucleophilic attack of the Grignard reagent onto the carbon atom of the O-alkyl thioformates, followed by the elimination of ROMgBr to generate aromatic thioaldehydes, which then react with a second molecule of the Grignard reagent at the sulfur atom to form arylsulfanyl benzylic Grignard reagents. To confirm the generation of aromatic thioaldehydes, the reaction between O-alkyl thioformates and phenyl Grignard reagent was carried out in the presence of cyclopentadiene. As a result, hetero-Diels-Alder adducts of the thioaldehyde and the diene were formed. The treatment of a mixture of the thioformate and phenyl Grignard reagent with iodine gave 1,2-bis(phenylsulfanyl)-1,2-diphenyl ethane as a product, which indicated the formation of arylsulfanyl benzylic Grignard reagents in the reaction mixture. When electrophiles were added to the Grignard reagents that were generated in situ, four-component coupling products, that is, O-alkyl thioformates, two molecules of Grignard reagents, and electrophiles, were obtained in moderate-to-good yields. The use of silyl chloride or allylic bromides gave the adducts within 5 min, whereas the reaction with benzylic halides required more than 30 min. The addition to carbonyl compounds was complete within 1 min and the use of lithium bromide as an additive enhanced the yields of the four-component coupling products. Finally, oxiranes and imines also participated in the coupling reaction.

Two new phenolic glycosides, kaempferiaosides A and B were isolated from the rhizomes of Kaempferia parviflora (Zingiberaceae) together with 24 known compounds. Their structures including absolute stereochemistry were elucidated on the basis of chemical and spectroscopic evidence. Among the isolates, 5,3'-dihydroxy-3,7,4'-trimethoxyflavone showed higher activity than silybin, a commercial hepatoprotective agent.

Four new ursane-type triterpenes, olibanumols K (1), L (2), M (3), and N (4), were isolated from traditional Egyptian medicine olibanum, the exuded gum-resin from Boswellia carterii BIRDW. Their structures were elucidated on the basis of chemical and physicochemical evidence.

Three iridoid glycosides, kankanosides L (I), M (II), and N (III), and two acyclic monoterpene glycosides, kankanosides O (IV) and P (V), are isolated from fresh stems of Cistanche tubulosa (Orobanchaceae) together with a multiplicity of known glycosides.

Bioassay-guided fractionation leads to the isolation of two new triterpene glycosides, bryoniaosides A (I) and B (II), along with several known structurally related substances.

BNF is found to be highly effective for the addition of arylboronic acids to aromatic aldehydes and is thus of interest in the preparation of bioactive diaryl methanols.

Among a variety of food materials, some are being used as resources of traditional, alternative, and/or complementary medicines all over the world. These medicinal foods are known to have not only nutritive and taste values but also medicinal effects, and they are prescribed in various traditional preparations. Regarding this point, we focused on exploring bioactive constituents in these medicinal foods, which would be applicable to remedy so-called metabolic syndrome. In this review, our recent studies on anti-hyperlipidemic saponin constituents from flowers of Bellis perennis are described.

Various metal oxides have been examined as catalysts for the hydrodechlorination of CFC-113 to form 1-chloro-1,2,2-trifluoroethylene (CFC-1113). NiO was most effective and over silica gel- or Y zeolite-supported Ni catalyst, 100% conversion of CFC-113 and 96% selectivity to CFC-1113 were attained.

The adsorbed state of benzene on Pd(110) at 300 K and its thermal decomposition process in the temperature region up to 700 K have been investigated by using high-resolution electron energy loss spectroscopy, low-energy electron diffraction, and multiplexed thermal desorption spectroscopy. Vibrational spectra show the existence of two adsorbed states of benzene on Pd(110) at 300 K. In one state, benzene is adsorbed with its C ring nearly parallel to the surface (flat benzene), and in the other state, at some angle (tilted benzene). The tilted benzene is located in the c(4{times}2) domains. For a small exposure ({approx lt}0.3 langmuir; fractional coverage {theta}{sub C{sub 6}H{sub 6}}{approx lt}0.07), the flat benzene predominates. With increasing exposure, conversion from flat to tilted benzene occurs, and the amount of tilted benzene is increased relative to that of flat benzene. For the saturation exposure (3 langmuirs: {theta}{sub C{sub 6}H{sub 6}} {approximately} 0.27), the tilted benzene predominates; the flat benzene also exists. Thermal decomposition of benzene on Pd(110) has been studied in detail. For a small exposure (0.3 langmuir), heating to 380-600 K forms the C{sub x}H{sub y}(x {ge} 1, y = 0,1) species as the decomposition products. By heating the sample to 600 K, theymore » find only C adatoms exist on Pd(110). For the saturation exposure (3 langmuirs), by heating the sample to 400 K, they find the C(4{times}2) structure is well developed and the Pd(110) surface is mostly covered by tilted benzene. Heating to 400-650 K forms the C{sub x}H{sub y} (x = 1 or {ge} 3, y = 0,1) species. The decomposition temperature is shifted toward higher temperatures by the site-blocking effect of benzene admolecules themselves. The decomposition is accompanied by h{sub 2} desorption.« less

Radical cyclizations were effectively applied to systems containing fluoroolefins (α-fluoro-α, β-unsaturated ester, fluoroallyl acetate, gem-difluoroolefin, and fluorine-substituted unsaturated lactone) for the synthesis of ring compounds containing fluorine-substituted groups.

Addition reactions of alkyl radicals to chiral (Z)-α,β-unsaturated ester derivatives obtained from (R)-2,3-O-isopropylidene glyceraldehyde proceeded with high stereoselectivity (1,2-asymmetric induction).

It was found that the skeletal rearrangement of unsaturated nitriles, such as methacrylonitrile to crotononitrile, took place readily over solid-base catalysts at the temperature range of 573 ∼ 673 K. MgO and CaO have shown high activity for the reaction, while acidic catalysts are inactive. The product distribution in the arrangement of trans -pent-3-enenitrile and the rearrangement of 13 C-labeled methacrylonitrile suggested that the reaction path involves an asymmetric anionic intermediate formed by methyl hydrogen abstraction by the surface base site and a subsequent CN-migration.

Simmons-Smith reactions of fluoroallyl alcohols and their derivatives with excess Zn-Cu and CH2I2 or Et2Zn and CH2I2 provided fluorocyclopropane derivatives. Diastereoselective cyclopropanation of the fluoroallyl alcohol derivative obtained from (R)-2, 3-O-isopropylidene glyceraldehyde was successfully carried out to give the optically active fluorocyclopropane derivative in high selectivity (>98% de).

Oligo-6-(2-thienyl)pentafulvenes, synthesized up to a tetramer by application of a new pentafulvene synthesis, show considerably low reduction potentials to suggest ready formation of polyanions or polyanion radicals with oligoacetylene spines.

Trifluoromethyl- or difluoromethylene-substituted alkyl radicals (CF 3 C or CF 2 C) and trifluoromethyl- substituted alkenyl radicals (CF 3 CC) cyclize effectively intramolecularly to allow the synthesis of fluorine- substituted cyclic compounds. Radical reactions of thiocarbonylimidazolide derivatives ( 7a,b, 13a–d, 14e,f ) gave CF 3 -substituted cyclopentane derivatives ( 22a, 25a–d ) or cyclohexane derivatives ( 22b, 26e,f ) via 5- or 6- exo selective cyclization. CF 3 -substituted cyclopentene derivatives ( 27a,b ) or cyclohexene derivatives ( 27c ) were also obtained from alkenyl iodides ( 17a–c ) via radical cyclization. Cyclopentane derivatives ( 29a–f, 31 ) containing the CF 2 CO 2 Et group were synthesized by Reformatsky reaction and radical cyclization.

Regio- and stereoselective formation of the functionalized gem-difluorocyclopropane derivative was achieved through the Michael addition of lithium enolate of ester or amide with 4-bromo-4,4-difluorocrotonate 1 followed by the triethylborane-O 2 mediated intramolecular substitution reaction.

Photodecomposition of dinitrogen oxide (N2O) into N2 and O2 on Cu-exchanged ZSM-5 zeolite (ion-exchange degree, 145 %), degassed at 723 K, proceeds catalytically at 278 K. The dependence of the decomposition rate on the wavelength of the irradiated light reveals the importance of the excitation of monovalent Cu ions (

Isolation and structure elucidation of four new oligoglycosides, epimeric kankanosides J (I) and K (II), resp., are described.

The Simmons-Smith reactions of Z- and E-allyl alcohol derivatives 6 derived from (R)-2,3-O-isopropylideneglyceraldehyde (6) were used for the synthesis of optically active cis- and trans-1,2-disubstituted cyclopropane derivatives. Reaction of 6 with diethyl zinc and diiodomethane gave cyclopropane derivatives 7 in 84% to quantitative yields with 35 to ≃100% des. Identical facial selectivities toward the double bonds, 1re-2si for Z-6 and 1re-2re for E-6, were observed in the cyclopropanations. The diastereoselectivity was dependent on the protecting group on the terminal allylic oxygen (R of 6, TBDPS>MOM>Bn) and on the stereochemistry of the double bond (Z >E). For TBDPS ethers Z-and E-6c, cis- and trans-7c were obtained as single distereomers, respectively. It was clearly demonstrated that the stereoselectivity of the cyclopropantion is controlled by the directing effect of the allylic oxygen (O-1) of the dioxolane ring, which coordinates to the reagent. The terminal allylic oxygen (O-2) lowered the diastereoselectivity. This reaction was applied to the synthesis of optically active cyclopropane analogs of γ-aminobutyric acid (GABA) 18,22, and ent-22

Sulfoxides carrying α-hydrogens were allowed to react with magnesium amides generated in situ by the treatment of ethylmagnesium bromide with secondary amines such as 2,2,6,6-tetramethylpiperidine or diisopropylamine in diethyl ether to give the corresponding dithioacetals in moderate to good yields.

The reactions of sulfoxides with magnesium amides generated in situ from the reaction of ethylmagnesium bromide and secondary amines, such as diisopropylamine (DIPA) or 2,2,6,6-tetramethylpiperidine (TMP) in diethyl ether, were examined. Diaryl sulfoxides were heated with the diisopropylaminomagnesium reagent in diethyl ether to give the corresponding diaryl sulfides in 42—52% yields. Sulfoxides bearing hydrogens at the α-positon only (RSOCH2R1) reacted with the tetramethylpiperidinomagnesium reagent at room temperature to produce the corresponding dithioacetals (RSCHR1SR) in 47—86% yields. The treatment of sulfoxides bearing hydrogens both at the α- and β-positions (RSOCHR1CHR2R3) with the magnesium amides at room temperature afforded the corresponding vinyl sulfides (RSCR1=CR2R3) in 52—72% yields accompanying 2.3—27% yields of the corresponding dithioacetals. The pathways leading to the products involving the formation of the sulfur-stabilized carbonium ion intermediates are discussed.

An efficient route to 1-formyl-1,2-dihydroquinolines 6 is described based on the BF3-catalyzed cyclization of o-(1-hydroxy-2-alkenyl)phenyl isocyanides 4, which can be prepared feasibly by the reaction of N-(o-acylphenyl)formamides 1 with alkenylmagnesium bromides 2 followed by treatment of the resulting hydroxy formamides 3 with phosphorous oxychloride.