Masaharu Toriyama

Stereochemistry of enantioselective deprotonation of 4-substituted cyclohexanones by chiral bidentate lithium amides

Abstract Enantioselective deprotonation of 4-substituted cyclohexanones (1) in the presence of excess trimethylsilyl chloride was examined using chiral bidentate lithium amides ((R)-3∼(R)-7) in THF. The solution structures of (R)-3a in THF in the presence and in the absence of lithium chloride were studied by NMR. It is concluded that the eight-membered cyclic transition state (10) offers reasonable explanation of the stereochemical course of the present reaction using (R)-3a.

Asymmetric Synthesis of γ-Hydroxy α-Enones by 1,8-Diazabicyclo[5.4.0]undec-7-ene-Catalyzed Stereoselective Rearrangement of Chiral α-Sulfinyl Enones

The asymmetric rearrangement of optically active alpha-sulfinyl enone 1 induced by catalytic DBU and triphenylphosphine gave optically active gamma-hydroxy alpha-enone derivatives (up to 99% ee) in good yield following treatment with aqueous hydrogen peroxide.

In Vitro and in Vivo Anti-Influenza Virus Activity of Diarylheptanoids Isolated from Alpinia Officinarum

Background: Diarylheptanoids (AO-0002 [7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl-4E-hepten-3-one] and AO-0011 [(5S)-5-hydroxy-7-(4″-hydroxyphenyl)-1-phenyl-3-heptanone]) isolated from Alpinia officinarum have been reported to exhibit anti-influenza virus activity in vitro. Hence, efficacies against influenza virus infection and the mode of antiviral action were evaluated in vivo and in vitro, respectively. Methods: In a murine influenza virus infection model, diarylheptanoids were orally administered three times daily to mice infected with influenza A/PR/8/34 virus for 6 days after infection. AO-0002 was examined for its antiviral activity against the wild types of influenza viruses A/PR/8/34 (H1N1), oseltamivir-resistant A/PR/8/34 (H1N1), A/Bangkok/93/03 (H1N1), A/Ishikawa/7/82 (H3N2), A/Fukushima/13/43 (H3N2), B/Singapore/222/79 and B/Fukushima/15/93 in plaque reduction or yield reduction assays. The mode of anti-influenza virus action was assessed by a virus adsorption assay, immunofluorescence assay of viral antigens, and inhibition of viral messenger RNA synthesis using real-time reverse transcriptase PCR. Results: AO-0002 at 100 mg/kg was significantly effective in reducing the body weight loss and prolonging survival times of infected mice without toxicity, but AO-0011 was not. AO-0002 at 30 and 100 mg/kg significantly reduced virus titres in bronchoalveolar lavage fluids of the lungs on days 3 and 6 after infection. AO-0002 exhibited anti-influenza virus activity against all viruses used, including the oseltamivir-resistant strain in vitro. The compound had no effect on virus adsorption or invasion into cells, but dose-dependently suppressed the expression of viral messenger RNA and antigens. Conclusions: AO-0002 was suggested to have a different anti-influenza virus action to that of oseltamivir and was verified to show anti-influenza activity in vitro and in vivo.

Stereochemically Controlled Asymmetric 1,2-Reduction of Enones Mediated by a Chiral Sulfoxide Moiety and a Lanthanum(III) Ion

Enantiomerically pure (Z)-β-sulfinyl allylic alcohols of either handedness can be readily prepared from (Z)-β-sulfinyl enones using NaBH(4) or DIBAL reductants in the presence of LaCl(3) as a chelating agent. A chiral sulfoxide auxiliary induces the remote 1,2-asymmetric reduction (1,4-induction) to afford various chiral allylic alcohols in high yields with excellent stereoselectivities (up to 100% de).

Antiviral activity of diarylheptanoid stereoisomers against respiratory syncytial virus in vitro and in vivo.

We previously showed that (5S)-5-hydroxy-7-(4-hydroxyphenyl)-1-phenylhept-3-one (AO-0011) and (5S)-5-methoxy-1,7-diphenylhept-3-one (AO-0016) isolated from Alpinia officinarum exhibited stronger anti-influenza virus activity and anti-respiratory syncytial virus (RSV) activity, respectively, than the other isolated diarylheptanoids. In this study, we synthesized an enantiomer (AO-0503) and racemate (AO-0504) of AO-0011 and an enantiomer (AO-0514) of AO-0016. The anti-RSV activities of the three stereoisomers (AO-0503, AO-0504, and AO-0514) and AO-0011 were examined in vitro and in vivo to evaluate the stereoisomeric effect on anti-RSV activity. In a plaque reduction assay using human epidermoid carcinoma cells, all four diarylheptanoids significantly exhibited anti-RSV activity, and AO-0514 and AO-0016 exhibited stronger anti-RSV activity than AO-0503, AO-0504, and AO-0011. In a murine RSV infection model, all four diarylheptanoids with anti-RSV activity in vitro were also significantly effective in reducing virus titers in the lungs of RSV-infected mice. In the histopathological analysis of RSV-infected lungs, the oral administration of even AO-0514, which showed the lowest reduction of virus titers in the lungs, was significantly effective in reducing the infiltration of lymphocytes and in reducing the interferon-γ level, which is a marker of severity of pneumonia due to RSV infection, in bronchoalveolar lavage fluids prepared from RSV-infected mice. Although the stereoisomeric effects of diarylheptanoids on anti-RSV activity varied moderately, all four diarylheptanoids examined were suggested to ameliorate pneumonia and have a potential anti-RSV activity in vivo. They are possibly mother compounds for the development of an anti-RSV drug in the future.

A Novel Synthesis of Cyclic Polythioethers Using Liquid-Liquid Phase-Transfer Catalysis

The synthesis of cyclic polythioethers has been achieved by the reactions of dithiols with alkyl dihalides. Thiols are not only hard to handle owing to their unpleasant smell, but also they are easily oxidizable, thus it is not easy to obtain various dithiols. However, we have developed a procedure for the preparation cyclic polythioethers by the reaction of dithioiminium salts with alkyl dihalides using phase-transfer catalyst without the use of dithiols, and have examined the ion recognition of these compounds.

Novel Synthesis of Optically Active 2‐Ethylhexanoic Acid, 2‐Ethylhexanol, and 2‐Ethylhexylamine via the Asymmetric Favorskii Rearrangement

Abstract The asymmetric Favorskii rearrangement of optically active α‐haloketones, which are easily prepared from chiral menthyl‐4‐toluenesulfoxide in several steps using primary or secondary amines, yields their corresponding secondary or tertiary chiral amides. The secondary chiral amides were converted to acids or amines using acylation followed by hydrolysis or reduction. In addition, the tertiary amides were directly reduced to alcohol with Super‐Hydride®.

A Facile Synthesis of Thioacids by Hydrolysis of 1-(Acylthio)ethaniminium Chlorides

A facile method for the preparation of thioacids in moderate to good yields has been developed by hydrolysis of 1-(acylthio)ethaniminium chlorides under a liquid-liquid two phase system consisting of benzene and a sodium hydroxide aqueous solution at room temperature. We have achieved facile preparation of these compounds without use of toxic compounds such as hydrogen sulfide.

Effect of Cell Differentiation for Neuroblastoma by Vitamin K Analogs

BACKGROUND Lack of receptor tyrosine kinase (TrkA), a high-affinity nerve growth factor (NGF) receptor, is closely associated with the malignant progression of neuroblastoma (NB) and its prognosis. Vitamin K3 (VK3) analogs inhibit the activity of protein tyrosine phosphatases (PTPases), which causes hydrolysis of the phosphate groups bound to the tyrosine residues on tyrosine kinase, resulting in sustained tyrosine phosphorylation. METHODS In order to reverse this abnormal NGF/TrkA signal transduction in NB cells, we synthesized new VK3 analogs and examined their activity against NB cells. RESULTS VK3 analogs increased or maintained the expression level of c-fos mRNA in the NB cells, which express the downstream genes of NGF/TrkA signal transduction. Moreover, the expression level of GAP-43 mRNA, which is a marker of neurite outgrowth and neuronal differentiation, was increased and morphological differentiation was also observed. VK3 analogs (especially COOH analog) continued to express c-fos and GAP-43 mRNAs and induced differentiation of NB cells after stimulation of NGF by strong inhibition of PTPase without affecting TrkA autophosphorylation. CONCLUSIONS Vitamin K3 analogs may have potential as clinical therapeutic agents for NB.

Multipoint Anchoring of the (2.2.2.2)Metacyclophane Motif to a Gold Surface via Self-Assembly: Coordination Chemistry of a Cyclic Tetraisocyanide Revisited

A one-pot transformation of bis(2-isocyano-3-methylphenyl)ethane affords gram quantities of 8,16,24,32-tetraisocyano[2.2.2.2]metacyclophane ( 3). The solid state structure of 3 is remarkably close to the lowest energy conformation found on the potential energy landscape for 3 by DFT. In solution, the structure of metacyclophane 3 is mobile but can be locked in a rectangular gauche- anti- gauche- anti conformation by coordination of the isocyanide substituents to the [W(CO) 5] units to give [M] 4(mu 4-eta (1):eta (1):eta (1):eta (1)- 3) ( 5). The tetranuclear [M] 4(mu 4-eta (1):eta (1):eta (1):eta (1)- 3) motif featured in crystallographically characterized 5 may be present in several insoluble complexes of 3 previously described as mononuclear eta (4) species. A self-assembled monolayer of metacyclophane 3 is formed upon exposing a solution of 3 to the gold(111) surface with no precautions to exclude air or light. The monolayer nature of the film was confirmed by optical ellipsometry. The isocyanide stretching band for 3 shifts from 2119 cm (-1) in solution to 2175 cm (-1) upon chemisorption to metallic gold. The FTIR spectrum of the film indicates interaction of 3 with the gold surface via all four of its isocyanide anchors. No gold-facilitated oxidation of the -NC junctions was detected under ambient conditions. The energy cost associated with accessing the conformations of 3 suitable for mu 4-eta (1):eta (1):eta (1):eta (1) interaction of the molecule with the Au(111) surface is under 8 kcal/mol, a value that can be easily offset by formation of a gold-isocyanide bond. Two different mu 4-eta (1):eta (1):eta (1):eta (1) coordination arrangements of 3 with respect to gold atoms on the (111) face of the fcc Au lattice are suggested.