A new norsesquiterpenoid from Russula delica Fr

Russulanorol (1), a new norsesquiterpenoid with a novel carbon skeleton, was isolated from the fruiting bodies of Russula delica FR. (Russulaceae) together with three known sesquiterpenoids. The structure of 1 was elucidated on the basis of spectral data and chemical transformation. Compound 1 is an equilibrium mixture of two stereoisomers (1a, b) on the C-11 acetal carbon.     

Parity of the Partition Function in Arithmetic Progressions, II

Let p(n) denote the ordinary partition function. Subbarao conjecturedthat in every arithmetic progression r (mod t) there are infinitelymany integers N = r (mod t) for which p(N) is even, and infinitelymany integers M = r (mod t) for which p(M) is odd. We provethe conjecture for every arithmetic progression whose modulusis a power of 2. 2000 Mathematics Subject Classification 11P83.     

In Vivo EPR Imaging of a Perfluoroalkyl Radical in Mouse Abdomen

Although it is thought that perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl (PFR-2) is a candidate for electron paramagnetic resonance (EPR) imaging agents because of its high stability, no study has been made yet on the EPR imaging of PFR-2. In this study, EPR imaging of a phantom including PFR-2 and mice that had received PFR-2 was performed by an in vivo EPR imaging system operating at an EPR frequency of 700 MHz equipped with a bridged loop-gap resonator (inner diameter, 41 mm; axial length, 10 mm). Because PFR-2 is insoluble in water, it was dissolved in perfluorocarbon. The PFR-2 solution was put in cylindrical sample tubes with various inner diameters, and these sample tubes were placed together in a larger cylindrical sample tube filled with a physiological saline solution, which was used as a phantom. The spatial resolution was estimated to be about 3 mm on the basis of EPR imaging of the phantom. EPR images of mice that had received a PFR-2 injection via the intraperitoneal route indicated that PFR-2 remained in the peritoneal cavity even 2 days after the injection. This finding suggests that it is possible to perform EPR imaging of experimental animals using PFR-2 as an imaging agent which persists in a biological system. Authors' address: Hidekatsu Yokoyama, National Institute of Advanced Industrial Science and Technology, 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya, Aichi 463-8560, Japan     

Splittings in the variety of residuated lattices

It is shown that the only algebra that splits the lattice of subvarieties of the variety of residuated lattices is the two element boolean algebra. Received October 4, 1999; accepted in final form August 11, 2000.     

Highly Pure Synthesis,Spectral Assignments,and Two‐Photon Properties of Cruciform Porphyrin Pentamers Fused with Benzene Units

Tetrameric porphyrin formation of 2‐hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene‐fused porphyrin pentamers. Thermal conversion of the pentamers gave fully π‐conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully π‐conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyrins. From TD‐DFT calculations, the HOMO level is 0.49 eV higher than the HOMO?1 level. The LUMO and LUMO+1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single‐electron transitions (683 nm: 86 %, HOMO→LUMO; 680 nm: 86 %, HOMO→LUMO+1). The two‐photon absorption (TPA) cross section value (σ⁽²⁾) of the benzene‐fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional π‐conjugation pathways.     

Study of transient photorefractive beam coupling in high- and low-molar-mass liquid crystal mixtures

We observed transient signals of Bragg grating formation in high-performance photorefractive high- and low-molar-mass liquid crystal mixtures (HL-LCMs). These transient signals including oscillation-like behavior can be explained by a complex time constant in the case of a finite applied dc field. The time constant for the space-charge field to reach its steady state and the oscillation frequency are estimated. Received: 30 October 1998 / Revised version: 14 December 1998 / Published online: 24 February 1999     

Catalytic activation of nucleophile precursors with metal acetates in alcohol media and applications to enantioselective Michael addition reactions

Nickel(II) acetate tetrahydrate works as catalyst to activate nucleophile precursors in Michael addition reactions. Use of alcohol media is essential for the high catalytic activation of nucleophile precursors. Catalytic enantioselective reactions using a chiral nickel(II) acetate tetrahydrate between dimedone and α,β-unsaturated amide acceptors provide a useful synthetic access to enantiomers of enol lactones through the carbon-carbon bond formation.