Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent-cis-195A and cis-211A

The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis-211A was determined to be 2R, 4aR, 5R, 6S, and 8aS. Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis-211A was the mirror image of that of cis-195A, although both alkaloids were isolated from the same poison frog species, Oophaga (Dendrobates) pumilio, from Panama.     

Complete Set of Deuteron Analyzing Powers for dp Elastic Scattering at Intermediate Energies and Three Nucleon Forces

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with the polarized deuteron beam at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron–proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon–nucleon forces together with the Tucson–Melbourne’99, and UrbanaIX three nucleon forces.     

Growth and Optical Properties of Tm:GdVO4 Single Crystal

Thulium-doped gadolinium vanadate (Tm:GdVO₄) single crystal has been successfully grown by a modified Czochralski (CZ) technique. Effective distribution coefficient of Tm was determined to be 0.74. Absorption characterization was performed in the 800 nm region and the maximum absorption peak was found at 799 nm for p polarization. Fluorescence spectra for tuning at the maximum absorption were obtained around 1.8-2.0µm region with 100 nm bandwidth. This suggests that a Tm:GdVO₄ crystal is expected as a new promising LD pumped solid-state laser in the 2µm region.     

Synthesis,Structure, and Spectroscopic Properties of [Feiii(tnpa)(OH)(PhCOO)]ClO4: A Model Complex for an Active Form of Soybean Lipoxygenase-1

The cis configuration between the hydroxo and the carboxylato and the three amino groups of the tetradentate, tripodal ligand tris(6-neopentylamino-2-pyridylmethyl)amine favors the formation of hydrogen bonds which stabilize the hydroxo–Feⁱⁱⁱ complex 1 . Thus, its structure closely resembles that of the active center of Feⁱⁱⁱ –soybean lipoxygenase-1, which also contains a six-coordinate Feⁱⁱⁱ atom.     

Stereocontrolled Synthesis of (11Z)-Retinal and Its Analogues

Suzuki coupling of stereochemically pure (Z)-bromotetraene 1 —which is extremely unstable but can be kept in frozen benzene in the presence of a small amount of PPh₃ at &sminus 01;20°C—and (Z)-alkenylboronic acid 2 provides the stereocontrolled synthesis of (11Z)-retinal 3 . The 11Z configuration, which is introduced by selective catalytic debromination of the corresponding dibromo precursor of 1 , is retained in this step. TBDMS = tBuMe₂Si.     

Synthesis and functionalities of poly(N-vinylalkylamide). IV. Synthesis and free radical polymerization of N-vinylisobutyramide and thermosensitive properties of the polymer

Pyrolysis of (N-α-isopropoxyethyl)isobutyramide, which was obtained by the reaction of isobutyramide, 2-propanol, and acetaldehyde in the presence of conc. sulfuric acid, produced N-vinylisobutyramide (NVIBA). The free radical polymerization of NVIBA was carried out in various solvents in the presence of a radical initiator. It was found that the polymerizability of NVIBA is similar to that of N-vinylacetamide. The resulting polyNVIBA showed a lower critical solution temperature (LCST) sharply at 39°C. Thermosensitive properties of polyNVIBA were investigated in comparison with poly(N-isopropylacrylamide). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1763–1768, 1997     

Low-coherence interferometer with 10 MHz repetition rate and compensation of nonlinear chromatic dispersion

Optical Review - We developed a low-coherence interference measurement system using the time-stretch dispersive Fourier transformation technique and demonstrated 10 MHz measurements of the...