8-Iodoisoquinolinone, a Conformationally Rigid Highly Reactive 2-Iodobenzamide Catalyst for the Oxidation of Alcohols by Hypervalent Iodine.

The first lactam-type 2-iodobenzamide catalysts, 8-iodoisoquinolinones 8 (IB-lactam) and 9 (MeO-IB-lactam), were developed. These catalysts have a conformationally rigid 6/6 bicyclic lactam structure and are more reactive than the previously reported catalysts 2-iodobenzamides 4 (IBamide) and 5 (MeO-IBamide) for the oxidation of alcohols. The lactam structure could form an efficient intramolecular I---O interaction, depending on the size of the lactam ring.

Efficient and Environmentally Benign Oxidative Cleavage of Pyrrolidine-2-methanols to γ-Lactams Using 2-Iodobenzamide as a Catalyst and Oxone.

The oxidative cleavage reaction of pyrrolidine-2-methanols to γ-lactams has been described. In this reaction, [4-iodo-3-(isopropylcarbamoyl)phenoxy]acetic acid and powdered Oxone (2KHSO5·KHSO4·K2SO4) were employed as the catalyst and co-oxidant, respectively. The reaction is efficient and environmentally benign because it produces various lactams from readily available substrates in moderate to excellent yields using organocatalyst and inorganic non-toxic co-oxidant.

Genetic engineering of eggplant accumulating ß-carotene in fruit.

KEY MESSAGE: Genetic engineering of eggplant using fruit-specific EEF48 promoter-driven bacterial PSY gene, crtB, confers ß-carotene accumulation in fruit. Eggplant (Solanum melongena L.) is globally cultivated especially in Asia and is an important source of nutrients in the diets of low-income consumers in developing countries. Since fruits of eggplant have low provitamin A carotenoid content, it is expected to develop eggplant with high carotenoid content for combatting vitamin A deficiency. To achieve this, the present study implemented a metabolic engineering strategy to modify the carotenoid biosynthetic pathway in eggplant. Expression analysis of carotenogenic genes in eggplant tissues showed that the expression of the endogenous phytoene synthase (PSY) was low in fruit and callus. Orange-colored calluses were generated from ectopic expression of crtB gene, which encodes bacterial PSY, in eggplant cells. The orange calluses accumulated > 20 µg g-1 FW of ß-carotene, which was approximately 150-fold higher than that of the untransformed calluses. These observations suggest that the PSY expression is the rate-limiting step for ß-carotene production in callus and fruit. Since the orange calluses did not regenerate plants, we chose eggplant EEF48 gene, which is presumably expressed in fruit. We amplified its promoter region by TAIL-PCR and showed that the EEF48 promoter is indeed active in eggplant fruit. Subsequently, transgenic eggplant lines having EEF48 promoter-driven crtB were produced. Among the transgenic lines produced, one line set fruit containing 1.50 µg g-1 FW of ß-carotene, which was 30-fold higher than that of the untransformed fruits (0.05 µg g-1 FW). The self-pollinated progenies showed a 3:1 segregation ratio for the presence and absence of the transgene, which was linked to the ß-carotene accumulation in fruit. These results provide a strategy for improvement of carotenoid content in eggplant fruit.

2-Iodo-N-isopropyl-5-methoxybenzamide as a highly reactive and environmentally benign catalyst for alcohol oxidation.

Several N-isopropyliodobenzamides were evaluated as catalysts for the oxidation of benzhydrol to benzophenone in the presence of Oxone® (2KHSO5·KHSO4·K2SO4) as a co-oxidant at room temperature. A study on the substituent effect of the benzene ring of N-isopropyl-2-iodobenzamide on the oxidation revealed that its reactivity increased in the following order of substitution: 5-NO2 < 5-CO2Me, 3-OMe < 5-OAc < 5-Cl < H, 4-OMe < 5-Me < 5-OMe. The oxidation of various benzylic and aliphatic alcohols using a catalytic amount of the most reactive 5-methoxy derivative successfully resulted in moderate to excellent yields of the corresponding carbonyl compounds. The high reactivity of the 5-methoxy derivative at room temperature is a result of the rapid generation of the pentavalent species from the trivalent species during the reaction. 5-Methoxy-2-iodobenzamide would be an efficient and environmentally benign catalyst for the oxidation of alcohols, especially benzylic alcohols.

Total Synthesis of Sphingofungin E and 4,5-Di-epi-sphingofungin E.

Total synthesis of sphingofungin E and 4,5-di-epi-sphingofungin E was achieved from an intermediate same as that of myriocin and mycestericin D via antipodal stereoselective dihydroxylations.

Beneficial effects of a gait used while wearing a kimono to decrease the knee adduction moment in healthy adults.

The knee adduction moment (KAM) relates to medial knee osteoarthritis (OA). Several gait modifications to reduce the KAM for the prevention of knee OA have been studied. Most of the modifications, however, involve voluntary changes in leg alignment. Here we investigated the biomechanical effects for reducing the KAM of a walking style with a small trunk rotation and arm swing gait, which is a natural walking style used while wearing a kimono (Nanba walk) that shifts the ground reaction force toward the stance leg (reduced lever arm). Twenty-nine healthy adults (21.5 ± 0.6 years) participated in the present study. A three-dimensional analysis system with 10 cameras and 1 force plate was used to obtain the KAM and other biomechanical data. Surface electromyography (EMG) of the hip and trunk muscles (internal obliquus abdominal muscle: IO, external obliquus abdominal muscle: EO, multifidus muscle: MF, and gluteus medius muscle: Gmed) was also assessed, and integrated EMG (iEMG) of the four muscles was assessed in the first and second halves of the stance phase. The 1st and 2nd peak KAMs were significantly decreased during Nanba walking (0.40±0.09 and 0.37±0.13 Nm/kg) compared with normal walking (0.45±0.09 and 0.45±0.13 Nm/kg; P = 0.002, P<0.001, respectively). The lever arm lengths at the 1st and 2nd peak KAMs were also significantly decreased during Nanba walking compared with normal walking (p = 0.023 and p<0.001, respectively). The iEMGs of IO, EO and Gmed muscles during the first half, and the iEMGs of EO and GM during the second half of the stance phase were significantly increased during Nanba walking compared with normal walking. The Nanba gait modification could be a useful strategy for reducing the KAM with high activation of the trunk and hip joint muscles for the prevention and/or treatment of medial knee OA.

Synthetic Studies on a Pachastrissamine Sulfur Analogue: Synthesis of a 4-epi-Sulfur Analogue.

A versatile synthetic procedure for a sulfur analogue of pachastrissamine (jaspine B), which involves the tandem thiolation-cyclization of a 1,4-ditosylate to construct a tetrahydrothiophene ring, was developed. Nucleophilic amino substitution of a tetrahydrothiophene-4-sulfonate with unexpected retention of the configuration afforded the sulfur analogue of 4-epi-pachastrissamine.

Practical Synthesis of Pachastrissamine (Jaspine B), 2-epi-Pachastrissamine, and the 2-epi-Pyrrolidine Analogue.

The practical syntheses of pachastrissamine (jaspine B), 2-epi-pachastrissamine, and the 2-epimer of the pyrrolidine analogue were accomplished via the stereoselective reduction of an allylketone derived from commercially available diethyl D-tartrate and the cross-metathesis of an allyltetrahydrofuran or allypyrrolidine with 1-tridecene as key steps.

Stepwise preparation of all-cis 1,3,4-trifluoro-2-phenylcyclohexane, avoiding a phenonium intermediate.

The original synthesis of all-cis 1,2,4,5,-tetrafluoro-2-phenylcyclohexane resulted in a trifluorocyclohexene as a significant co-product of the final fluorination step. This product was notable in that an elimination reaction was accompanied by C-F bond formation that had occurred with a retention of configuration. In order to deconvolute this reaction, the two isomers of the ditriflate diol precursor were separated, and they were each treated independently with Et3N·3HF. One gave the original all-cis 1,2,4,5,-tetrafluoro-2-phenylcyclohexane and the other the trifluorocyclohexene. A deuterium labeling experiment was carried out, resulting in a distribution of the isotope in the trifluorocyclohexene consistent with an intermediate (symmetrical) phenonium intermediate. Cognisant of this, a controlled elimination reaction of one of the diastereoisomers with DBU, followed by hydrogenation, gave a cyclohexane triflate, which, on fluorination, gave the all-cis 1,2,3-trifluoro-2-phenylcyclohexane now with an inversion of configuration.

Synthesis and elaboration of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane: a polar cyclohexane motif.

A stereocontrolled synthesis of all-cis-1,2,4,5- tetrafluoro-3-phenylcyclohexane is developed as the first functionalised example of this polar cyclohexane motif. The dipolar nature of the ring, arising due to two 1,3-diaxial C-F bonds, is revealed in the solid-state (X-ray) structure. The orthogonal conformation of the aryl and cyclohexyl rings in all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane, and in an ortho-nitro derivative, result in intramolecular (1h)JHF and (2h)JCF  NMR couplings relayed through hydrogen bonding. The aryl group of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane is elaborated in different ways to demonstrate the versatility of this compound for delivering the motif to a range of molecular building blocks.

Confirmation by IR of the preferred conformations of CFTA esters in solution: a highly reliable criterion for the stereochemistry assignment of chiral alcohols.

Direct confirmation of the preferred conformation of diastereomeric esters derived from a chiral secondary alcohol and a chiral derivatizing agent in solution, which is crucial for reliable NMR-based assignment of absolute stereochemistry of the alcohol, has been attained for the first time by examination of IR spectra of the CFTA esters.

Possible involvement of radical intermediates in the inhibition of cysteine proteases by allenyl esters and amides.

In order to investigate crystallographically the mechanism of inhibition of cysteine protease by alpha-methyl-gamma,gamma-diphenylallenecarboxylic acid ethyl ester 3, a cysteine protease inhibitor having in vivo stability, we synthesized N-(alpha-methyl-gamma,gamma-diphenylallenecarbonyl)-L-phenylalanine ethyl ester 4. Reaction of 4 with thiophenol, the SH group of which has similar pK(a) value to that of cysteine protease, produced oxygen-mediated radical adducts 6 and 7 in ambient air but did not proceed under oxygen-free conditions. Catalytic activities of two thiol enzymes including cathepsin B were also lowered in the absence of oxygen. These results suggest that cysteine protease can act through an oxygen-dependent radical mechanism.

Design of antiangiogenic hypoxic cell radiosensitizers: 2-nitroimidazoles containing a 2-aminomethylene-4-cyclopentene-1,3-dione moiety.

We designed chiral 2-nitroimidazole derivatives containing a 2-aminomethylene-4-cyclopentene-1,3-dione moiety as antiangiogenic hypoxic cell radiosensitizers. Based on results of molecular orbital calculations, the 2-aminomethylene-4-cyclopentene-1,3-dione moiety is expected to show high electrophilicity comparable to that of the 2-methylene-4-cyclopentene-1,3-dione moiety included in TX-1123 and tyrphostin AG17. We evaluated the antiangiogenic and radiosensitizing effects of the new compounds, along with other biological properties including their activities as hypoxic cytotoxicities and protein tyrosine kinase (PTK) inhibitory activities. Among the compounds tested, 5 (TX-2036) proved to be the strongest antiangiogenic hypoxic cell radiosensitizer. All the other chiral 2-nitroimidazole derivatives having 2-aminomethylene-4-cyclopentene-1,3-dione moiety tested were also antiangiogenic hypoxic cell radiosensitizers. The PTK inhibitory activity of 5 (TX-2036) showed this to be a promising and potent EGFR kinase inhibitor, having an IC(50) value of lower than 2microM. This compound also was an Flt-1 kinase inhibitor having an IC(50) value of lower than 20microM. Our results show that these chiral 2-nitroimidazole derivatives that contain the 2-aminomethylene-4-cyclopentene-1,3-dione moiety as a potent antiangiogenic pharmacophoric descriptor are promising lead candidates for the development of antiangiogenic hypoxic cell radiosensitizers.

Synthetic Studies of 3-(3-Fluorooxindol-3-yl)-l-alanine.

Oxidative fluorination of several protected tryptophans 8b-g with Selectfluor proceeded smoothly in aqueous media to give a diastereomeric mixture of the corresponding 3-fluorooxindoles 9b-g. Attempted deprotection of the 3-fluorooxindoles 9b-g under various conditions did not afford 3-(3-fluorooxindol-3-yl)-l-alanine (6). Reaction of the suitably protected tryptophan derivative 16 with Selectfluor produced the fluorinated product 17. Simultaneous cleavage of all protective groups of 17 under acidic conditions successfully gave the target compound 6 in excellent yield.

The origin of an unusually large 19F chemical shift difference between the diastereomeric alpha-cyano-alpha-fluoro-p-tolylacetic acid (CFTA) esters of 3',4',5,7-tetra-O-methylepicatechin.

During a study on the relationship between the (19)F chemical shift difference for the diastereomeric alpha-cyano-alpha-fluoro-p-tolylacetic acid (CFTA) esters of chiral secondary alcohols and the absolute configurations of the alcohols, an unusually large 19F chemical shift difference has been observed for the CFTA esters of 3',4',5,7-tetra-O-methylepicatechin. This large chemical shift difference has been reproduced by ab initio calculations of molecular geometry and GIAO calculations of 19F chemical shifts on the stable conformations of the diastereomeric alpha-cyano-alpha-fluorophenylacetic acid (CFPA) esters of cis-flavan-3-ol as model systems. The origin of the large chemical shift difference has been further investigated using NBO analysis. This revealed that the interaction between pi(C=C) of the aryl group in the chiral auxiliary and sigma*(C--F) is a very important determinant of the 19F chemical shifts and this interaction depends on the torsion angle between the plane of aryl group and the C--F bond.

Biological evaluation of 2-aryl-2-fluoropropionic acids as possible platforms for new medicinal agents.

We investigated the cyclooxygenase (COX) inhibitory and anticancer activities of 2-aryl-2-fluoropropionic acids 1a-e. These fluorinated compounds showed lower inhibitory activity toward COX-1 than the corresponding non-fluorinated compounds 2a-e with retained inhibitory activity against COX-2 resulting in modification of the balance of COX-1/COX-2 inhibitions, and they showed little anticancer activity. Interesting differences of the activities between (S)- and (R)-enantiomers were observed in some cases.

Synthesis and optical resolution of 2-aryl-2-fluoropropionic acids, fluorinated analogues of non-steroidal anti-inflammatory drugs (NSAIDs).

We report the synthesis of optically active 2-aryl-2-fluoropropionic acids 2 as non-epimerizable mimics of 2-arylpropionic acids 1, a class of compounds which have been widely used as non-steroidal anti-inflammatory drugs (NSAIDs). This is a continuation of our research involving the design, synthesis, and evaluation of chiral fluorine-containing organic molecules as effective analogues of pharmacologically important compounds.