Studies on the syntheses of heterocyclic compounds. Part DCXLIV . Catalytic reduction of homoproaporphine related compounds

Hydrogenation of the homoproaporphine (IV) over platinum oxide gave a mixture of the cyclohexanols VIIa and VIIb. In contrast, reduction of IV on palladium provided the cyclo-hexanone VI, which was also obtained from VIIb by oxidation. Treatment of the cyclohexanols VIIa and VIIb under hydrogen on platinum oxide afforded the same mixture of VIIa and VIIb.     

Photooxygenation of pyrazin-2(1h)-ones

1-Alkyl-5,6-diphenylpyra2in-2(1H)-ones (1a-b) reacted with singlet oxygen in dichloromethane to afford the stable endoperoxide (1a-b), while in methanol to afford the 1:1-adduct (3a-b) of the endoperoxide (2a-b) and methanol.     

Determination of peptide φ angles in solids by relayed anisotropy correlation NMR

A solid state NMR method is presented for determination of a backbone dihedral angle φ in peptides, being based on the previously reported method, relayed anisotropy correlation (RACO) NMR [Y. Ishii et al., Chem. Phys. Lett. 256 (1996) 133]. In the present method, the and the dipolar tensors in the system are two-dimensionally (2D) correlated via polarization transfer from to under magic angle spinning (MAS). This method was applied to N-acetyl , -valine, and the H–C–N–H dihedral angle was determined to be 154.0±1.4° or 206.0±1.4°, the former agreeing with the X-ray value of 154±5°.     

1-Phosphacephalosporin. I. Synthesis of racemic 7-unsubstituted-1-phosphadethia-3-cephem 1-oxides

The novel unnatural ring system, 1-phosphacephalosporin, was synthesized for the first time from 4-acetoxy-2-azetidinone.     

Calculation of A Λp invariant-mass distribution in the reaction K−d → π−Λp

The Λp invariant-mass distribution in the reaction K^?d → π^?Λp, which is observed Cline et al., has two enhancements: just below the ΣN threshold and just above the ΛN threshold. We have calculated the Λp invariant mass distribution with the two-channel formalism. It has been well discussed in our previous paper that the enhancement just below the ΣN threshold is mainly due to a Λp resonance. In our previous paper, we have interpreted the enhancement just above the ΛN threshold as the two-channel final state interaction or a Λp final state interaction associated with the ΣΛ conversion process. The physical meaning will be intensively discussed in this paper. In fact, we have clearly shown, in this paper, that the effect due to the ΣΛ conversion process is in the enhancement just above the ΛN threshold. If the experimental data should be interpreted by the two-step process K^?d → π^?(ΣN) → π^?Λp, the effect due to the ΣΛ conversion process should have appeared in the experimental data, although some experimental data do not show the enhancement just above the ΛN threshold.     

Stereoselective synthesis of (±)-phomenone,a phytotoxic metabolite of phoma exigua, and (±)-3-epiphomenone

Stereoselective synthesis of (±)-phomenone, a phytotoxic metabolite from the fungus Phoma exigua, and (±)-3-epiphomenone is described.     

Electronic structure of the organic conductors based on BMDT-TTF (BIS(methylenedithio)tetrathiafulvalene)

In the crystals of the cation radical salts based on the organic donor BMDT-TTF, the charge separation is observed. This comes from (1) nonequivalency of the site potential and (2) the long range electron-electron interaction, which are related to the two-dimensional nature of the molecular arrangement. The effects of the charge separation on the elctronic structure are discussed.     

Non-additivity for triple point numbers on the connected sum of surface-knots

Any surface-knot in 4-space can be projected into 3-space with a finite number of triple points, and its triple point number, , is defined similarly to the crossing number of a classical knot. By definition, we have for the connected sum. In this paper, we give infinitely many pairs of surface-knots for which this equality does not hold.