Reactions of Methyl 1-(Bromoacetyl)azulene-3-carboxylate with Thioamides and Thioureas: Synthesis of 1-(Thiazol-4-yl)-3-methoxycarbonylazulenes

Thiazole derivatives have attracted a great deal of interest owing to their physiological activities. In addition, thiazoles are also useful in dye and photographic industry.[1] In the present paper we report the synthesis of azulenes containing a thiazole moiety.     

Reactions of 3-isopropenyltropolones with bromine and N-bromosuccinimide: Formation of 8H-cyclohepta[b]furan-8-one derivatives

3-Isopropenyltropolones 1a-c were treated with bromine in carbon tetrachloride to give 3-methyl-8H-cyclohepta[b]furan-8-ones 2a-c and their corresponding 7-bromo-substituted compounds 3a-c , while reactions in acetic acid gave the bromo-substituted compounds 3a-c . On the other hand, bromination of 1a-c with N-bromosuccinimide afforded 7-bromo-3-(2-bromo-1-methylethenyl)tropolones 5a-c . The compound 2a was treated with bromine to give 2-bromo-3-methyl-8H-cyclohepta[b]furan-8-one ( 4 ). The tropolones 5a-c were heated in the presence of potassium carbonate to give the cyclized compounds 3a-c .     

Preparation, structure, and magnetic interaction of a Mn(hfac)2-bridged [2-(3-pyridyl)(nitronyl nitroxide)-Mn(hfac)2]2 chain complex

A new one-dimensional chain complex, Mn(hfac)(2)-bridged [2-(3-pyridyl)(nitronyl nitroxide)Mn(hfac)(2)](2), was prepared and its structure and magnetic properties were elucidated; the complex exhibited a large antiferromagnetic interaction of J(1)=-185 K between the three Mn(ii) atoms and the two nitronyl nitroxides to give S=13/2 spin units and a small ferromagnetic interaction of J(3)'=+0.02 K between these spin units at low temperatures (50-1.9 K), compatible with the theoretical analysis for model compounds.     

On the robust thermodynamical structures against arbitrary entropy form and energy mean value

We discuss how the thermodynamical Legendre transform structure can be retained not only for the arbitrary entropic form but also for the arbitrary form of the energy constraints by following the discussion of Plastino and Plastino. The thermodynamic relation between the expectation values and the conjugate Lagrange multipliers are seen to be universal. Furthermore, Gibbs' fundamental equation is shown to be unaffected by the choice of the entropy and the definition of the mean values due to the robustness of the Legendre transform structure. Received 28 April 2000 and Received in final form 29 July 2000     

Stereoselective synthesis of optically active 3-hydroxy-7,8-dihydro-beta-ionol-glucosides

A stereocontrolled synthesis of optically active beta-D-glucopyronosides 6a, b and 11a, b was accomplished via the 7,8-saturated alcohols 4a, b, efficiently prepared by an asymmetric transfer hydrogenation of the alpha,beta-acetylenic ketone 1 and subsequent catalytic hydrogenation. Simultaneous separation of these four glucosides by HPLC was also performed. This work is useful not only in order to confirm the stereochemistries of the trace amount of glucosides in plants but also to clarify their biosynthesis.     

Absorption spectrum of nitrous acid for the ν1+2ν3 band studied with continuous-wave cavity ring-down spectroscopy and theoretical calculations

We present the high resolution absorption measurements of gaseous HONO at room temperature using continuous-wave cavity ring-down spectroscopy in the near-infrared region between 6017 and 6067 cm⁻¹ at a resolution of 1 pm (0.037 cm⁻¹). For the trans-HONO isomer an extensive analysis of the ν₁+2ν₃ combination band 6045.8089 cm^–1 was performed starting from the results of a previous study for the 1¹ and 3¹ vibrational states [Guilmot J-M, Godefroid M, Herman M. Rovibrational parameters for trans-nitrous acid. J Mol Spectrosc 1993;160:387–400]. The present combination band is perturbed because of the existence of several dark states of HONO which could not be identified unambiguously. The rotational constants achieved for the 1¹3² state deviate slightly from the values which are predicted from the rotational constants achieved in the previous studies for the 1¹ and 3¹ vibrational states of trans-HONO.     

Image Compression Using an Improved Optical Inner Product Processor

We show a prototype of a coding system for image compression using vector quantization with an optical inner product processor, whose accuracy is improved by the applying data transformation method. We also present compression effects for gray-scaled images by this system. The system can compress 256X256X8 bits image data within 1.2 seconds under 0.18 compression ratio with an adequate quality.     

Synthesis and reactions of 1,3-dicarbonyl-substituted troponoids: Conversion to tropolones having an isoxazole or a pyrazole ring

3-Acetyltropolone ( 1 ) was treated with diethyl oxalate in the presence of sodium ethoxide to afford 3-(2-ethoxalyl-1-oxoethyl)tropolone ( 2 ) as a minor product and its cyclized 2-ethoxycarbonyl-4,9-dihydrocyclohetpa[b]pyran-4,9-dione ( 3 ) as the major one. The former was readily converted to the latter. Then, as a stable synthon bearing a 1,3-dicarbonyl group, 2-(2-ethoxalyl-1-oxoethyl)-7-methylaminotropone ( 5 ) was prepared. The reactions of compound 5 with hydroxylamine, hydrazine, and methylhydrazine were carried out to give troponoids possessing an isoxazole or a pyrazole ring. The parent compounds, 3-(3-pyrazolyl)tropolone ( 13 ) and 3-(1-methylpyrazol-3-yl)tropolone ( 21 ), were obtained via hydrolysis and decarboxylation. Similarly, 2-ethoxycarbonyl-4,9-dihydrocyclohepta[b]pyran-4,9-dione ( 3 ) reacted with hydroxylamine, hydrazine, and methylhydrazine to yield troponoids possessing a heterocyclic ring.     

Strong interference of sound pressure generated by vortex soliton with axial flow

Sound pressure generated by a thin vortex filament with axial flow is investigated on the base of soliton theory. The pressure is estimated by using the experimental results of Maxworthy et al. [J. Fluid Mech. 151, 141] where one-soliton propagation and head-on collision of two solitons are observed. Collision of two solitons gives rise to very enhanced interference of the sound pressure.     

Long-term Effects of 222-nm ultraviolet radiation C Sterilizing Lamps on Mice Susceptible to Ultraviolet Radiation

Germicidal lamps that emit primarily 254 nm ultraviolet radiation (UV) are routinely utilized for surface sterilization but cannot be used for human skin because they cause genotoxicity. As an alternative, 222-nm UVC has been reported to exert sterilizing ability comparable to that of 254-nm UVC without producing cyclobutane pyrimidine dimers (CPDs), the major DNA lesions caused by UV. However, there has been no clear evidence for safety in chronic exposure to skin, particularly with respect to carcinogenesis. We therefore investigated the long-term effects of 222-nm UVC on skin using a highly photocarcinogenic phenotype mice that lack xeroderma pigmentosum complementation group A (Xpa-) gene, which is involved in repairing of CPDs. CPDs formation was recognized only uppermost layer of epidermis even with high dose of 222-nm UVC exposure. No tumors were observed in Xpa-knockout mice and wild-type mice by repetitive irradiation with 222-nm UVC, using a protocol which had shown to produce tumor in Xpa-knockout mice irradiated with broad-band UVB. Furthermore, erythema and ear swelling were not observed in both genotype mice following 222-nm UVC exposure. Our data suggest that 222-nm UVC lamps can be safely used for sterilizing human skin as far as the perspective of skin cancer development.