Asymmetric synthesis of abietane diterpenoids via B-alkyl Suzuki-Miyaura coupling. Formal total asymmetric synthesis of 12-deoxyroyleanone and cryptoquinone

A convergent synthetic strategy for abietane diterpenoids via B-alkyl Suzuki-Miyaura coupling and Lewis acid-mediated cyclization reactions is established. Asymmetric total synthesis of 12-deoxyroyleanone, an antileishmanial diterpene, is described.     

Synthesis and absolute configuration of cordiaquinone K, antifungal and larvicidal meroterpenoid isolated from the Panamanian plant, Cordia curassavica

Total synthesis of cordiaquinone K, a new antifungal and larvicidal meroterpenoid, is reported. The absolute configuration of cordiaquinone K was confirmed by the synthesis.     

Structures and conformations of metabolites of antitumor cyclic hexapeptides, RA-VII and RA-X.

Metabolites of antitumor cyclic hexapeptides, RA-VII and -X which were isolated from Rubia cordifolia were studied by hepatic microsomal biotransformation in rats and in bile juice of rabbits to which these drugs were administered intravascularly. Their structures and conformations were elucidated by two-dimensional nuclear magnetic resonance techniques, temperature effect on NH protons and nuclear Overhauser effect experiments. Specific N-demethylation of Tyr-3, O-demethylation and hydroxylation at aromatic rings of Tyr-3 and -5 were observed. Compared with metabolites of RA-VII, most of RA-X was excreted unchanged in the bile juice. Relationship among their structures, conformations and antitumor activities is also discussed.     

Asymmetric synthesis of the hydronaphthalene moieties of mevinic acids

The hydronaphthalene moieties of mevinic acids are synthesized enantioselectively by using the asymmetric intramolecular Diels-Alder reaction catalyzed by a chiral titanium reagent.     

Donor–acceptor–acceptor-type near-infrared fluorophores that contain dithienophosphole oxide and boryl groups: effect of the boryl group on the nonradiative decay

The use of donor–π–acceptor (D–π–A) skeletons is an effective strategy for the design of fluorophores with red-shifted emission. In particular, the use of amino and boryl moieties as the electron-donating and -accepting groups, respectively, can produce dyes that exhibit high fluorescence and solvatochromism. Herein, we introduce a dithienophosphole P-oxide scaffold as an acceptor–spacer to produce a boryl- and amino-substituted donor–acceptor–acceptor (D–A–A) π-system. The thus obtained fluorophores exhibit emission in the near-infrared (NIR) region, while maintaining high fluorescence quantum yields even in polar solvents (e.g. λ_em = 704 nm and Φ_F = 0.69 in CH₃CN). A comparison of these compounds with their formyl- or cyano-substituted counterparts demonstrated the importance of the boryl group for generating intense emission. The differences among these electron-accepting substituents were examined in detail using theoretical calculations, which revealed the crucial role of the boryl group in lowering the nonradiative decay rate constant by decreasing the non-adiabatic coupling in the internal conversion process. The D–A–A framework was further fine-tuned to improve the photostability. One of these D–A–A dyes was successfully used in bioimaging to visualize the blood vessels of Japanese medaka larvae and mouse brain.

Combination of electron-accepting diarylboryl terminal groups and dithienophosphole oxide spacers with electron-donating triarylamine moieties produces donor–acceptor–acceptor type π-systems, which exhibit emissions in the near-infrared region.     

Asymmetric synthesis of bicyclo[n.1.0]alkanes by the enantioselective 1,3-CH insertion reaction of chiral magnesium carbenoids

Treatment of enantiomerically pure 1-chlorovinyl p-tolyl sulfoxides, derived from cyclic ketones and (R)-chloromethyl p-tolyl sulfoxide, with the lithium enolate of tert-butyl carboxylates gave adducts in quantitative yields as single diastereomers. The adducts were treated with i-PrMgCl in toluene to afford optically active bicyclo[n.1.0]alkanes bearing a tert-butyl carboxylate moiety in up to 99% enantiomeric excess through the enantioselective 1,3-CH insertion reaction of the generated chiral magnesium carbenoids. This is the first example of the enantioselective 1,3-CH insertion reaction of magnesium carbenoid.     

iVDR business perspective

This paper describes a perspective for information versatile disk for removable usage (iVDR) business. iVDR is the best bridge media for high-resolution image because of high capacity and high reliability. The first iVDR product was delivered with PMR technology hard disk drives and a copyright protection function for high-definition TV programs. The business opportunity and the new business model are discussed.     

The unification of inflation and late-time acceleration in the frame of <Emphasis Type="Italic">k</Emphasis>-essence

By using the formulation of the reconstruction, we explicitly construct models of k-essence, which unify the inflation in the early universe and the late accelerating expansion of the present universe by a single scalar field. Due to the higher derivative terms, the solution describing the unification can be stable in the space of solutions, which makes the restriction for the initial condition relaxed. The higher derivative terms also eliminate tachyon. Therefore we can construct a model describing the time development, which cannot be realized by a usual inflaton or quintessence models of the canonical scalar field due to the instability or the existence of tachyon. We also propose a mechanism of the reheating by the quantum effects coming from the variation of the energy density of the scalar field.     

Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing β‐Diketone and Schiff Bases

The UV, excitation, and luminescence spectra of tris(pivaloyltrifluoroacetonato)europium(III) ([Eu(pta)₃]; Hpta=1,1,1‐trifluoro‐5,5‐dimethylhexane‐2,4‐dione=HA) were measured in the presence of bis(salicylidene)trimethylenediamine (H₂saltn), bis[5‐(tert‐butyl)salicylidene]trimethylenediamine (H₂(^tBu)saltn), or bis(salicylidene)cyclohexane‐1,2‐diyldiamine (H₂salchn), and the corresponding Zn^II complexes [ZnB] (B=Schiff base). The excitation and luminescence spectra of the solution containing [Eu(pta)₃] and [Zn(salchn)] exhibited much stronger intensities than those of solutions containing the other [ZnB] complexes. The introduction of a ^tBu group into the Schiff base was not effective in sensitizing the luminescence of [Eu(pta)₃]. The luminescence spectrum of [ZnB] showed a band around 450 nm. The intensity decreased in the presence of [Eu(pta)₃], reflecting complexation between [Eu(pta)₃] and [ZnB]. On the basis of the change in intensity against the concentration of [ZnB], stability constants were determined for [Eu(pta)₃Zn(saltn)], [Eu(pta)₃Zn{(^tBu)saltn}], and [Eu(pta)₃Zn(salchn)] as 4.13, 4.9 and 5.56, respectively (log , where =[[Eu(pta)₃ZnB]]([[Eu(pta)₃]][[ZnB]])^?1). The quantum yields of these binuclear complexes were determined as 0.15, 0.11, and 0.035, although [Eu(pta)₃Zn(salchn)] revealed the strongest luminescence at 613 nm. The results of X‐ray diffraction analysis for [Eu(pta)₃Zn(saltn)] showed that Zn^II had a coordination number of five and was bridged with Eu^III by three donor O‐atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta.     

Computer-Aided Detection of Quantitative Signatures for Breast Fibroepithelial Tumors Using Label-Free Multi-Photon Imaging

Fibroadenomas (FAs) and phyllodes tumors (PTs) are major benign breast tumors, pathologically classified as fibroepithelial tumors. Although the clinical management of PTs differs from FAs, distinction by core needle biopsy diagnoses is still challenging. Here, a combined technique of label-free imaging with multi-photon microscopy and artificial intelligence was applied to detect quantitative signatures that differentiate fibroepithelial lesions. Multi-photon excited autofluorescence and second harmonic generation (SHG) signals were detected in tissue sections. A pixel-wise semantic segmentation method using a deep learning framework was used to separate epithelial and stromal regions automatically. The epithelial to stromal area ratio and the collagen SHG signal strength were investigated for their ability to distinguish fibroepithelial lesions. An image segmentation analysis with a pixel-wise semantic segmentation framework using a deep convolutional neural network showed the accurate separation of epithelial and stromal regions. A further investigation, to determine if scoring the epithelial to stromal area ratio and the SHG signal strength within the stromal area could be a marker for differentiating fibroepithelial tumors, showed accurate classification. Therefore, molecular and morphological changes, detected through the assistance of computational and label-free multi-photon imaging techniques, enable us to propose quantitative signatures for epithelial and stromal alterations in breast tissues.