Saowanit Saithong

Photoactive azoimine dyes: 4-(2-Pyridylazo)-N,N-diethylaniline and 4-(2-pyridylazo)-N,N-dimethylaniline: Computational and experimental investigation

4-(2-Pyridylazo)-N,N-dimethylaniline and 4-(2-pyridylazo)-N,N-diethylaniline, two photoactive azoimine dyes, were prepared from the reaction of 2-aminopyridine with N,N-dialkyl-1,4-nitrosoaniline at room temperature. Structural characterizations of these dyes using single crystal X-ray diffraction, (1)H NMR, elemental analysis, mass spectroscopy and IR spectroscopy have been carried out. The X-ray structure indicates a trans configuration around the azo group. The photochemical behavior of these compounds differs from that of 2-phenylazopyridine, the non-dialkylamino substituent compound. The synthesized compounds show emission spectra at room temperature while 2-phenylazopyridine does not. The excitation spectra of these compounds differ from their absorption spectra which can be explained on the basis of the trans to cis photoisomerization which is supported by the TD-PBE0/6-31G(d,p) calculations. Both oxidation of the dialkylamino substituents (-NR(2); R=-CH(3) and -C(2)H(5)) and reduction of -N=N-/-N=N-(-) and -N=N-(-)/-N=N-(2-) were observed in the cyclic voltammogram indicating a π-acidity of both dyes.

Lovastatin Analogues from the Soil-Derived Fungus Aspergillus sclerotiorum PSU-RSPG178.

Three new lovastatin analogues (1, 4, and 5) together with four known lovastatin derivatives, namely, lovastatin (2), α,β-dehydrolovastatin (3), α,β-dehydrodihydromonacolin K (6), and α,β-dehydro-4a,5-dihydromonacolin L (7), were isolated from the soil-derived fungus Aspergillus sclerotiorum PSU-RSPG178. Their structures were established using spectroscopic evidence. Compound 5 exhibited the most potent activity against HMG-CoA reductase, with an IC50 value of 387 μM. In addition, the present study indicated the direct interaction of compound 5 with HMG-CoA reductase. Compound 5 was considered to be noncytotoxic against noncancerous Vero cells, with an IC50 value of 40.0 μM, whereas compound 2 displayed much stronger activity, with an IC50 value of 2.2 μM.

Synthesis of gem-difluoromethylenated polycyclic cage compounds.

The synthesis of gem-difluoromethylenated polycyclic cage compounds, utilizing PhSCF2SiMe3 as a gem-difluoromethylene building block, is described. The fluoride-catalyzed nucleophilic addition of PhSCF2SiMe3 to both maleic anhydride-cyclopentadiene and maleic anhydride-cyclohexadiene adducts was accomplished with high stereoselectivity to provide the corresponding adducts that were treated with Grignard reagents, followed by acid-catalyzed lactonization to afford the corresponding γ-butyrolactones, each as a single isomer. These γ-butyrolactones underwent intramolecular radical cyclization to give the corresponding tetracyclic cage γ-butyrolactones, which were employed as precursors for the synthesis of gem-difluoromethylenated tetracyclic cage lactols or tetracyclic cage furans, upon treatment with Grignard reagents.

3,4,5-Trihy-droxy-benzoic acid.

In the title compound, C7H6O5, the three hydroxy groups on the ring are oriented in the same direction. There are two intramolecular O—H⋯O hydrogen bonds in the ring. In the crystal, there are several intermolecular O—H⋯O hydrogen bonds and a short contact of 2.7150 (18) Å between the O atoms of the para-OH groups of adjacent molecules.

Terezine derivatives from the fungus Phoma herbarum PSU-H256

Investigation of the fungus Phoma herbarum PSU-H256 isolated from a leaf of Hevea brasiliensis resulted in the isolation of eight terezine derivatives (E-L) together with four known compounds. Their structures were established by analysis of spectroscopic evidence. For terezines E and H, their structures were confirmed by single-crystal X-ray diffraction crystallography. In addition, the absolute configuration at C-7 in terezine E was established by Moshers method. Terezines K and L were tested for antibacterial, antimalarial, antimycobacterial and cytotoxic activities, but were inactive.

Biotransformation of ent-kaur-16-en-19-oic acid by Absidia blakesleeana and Rhizopus oligosporus

Biotransformation of ent-kaur-16-en-19-oic acid was carried out with Absidia blakesleeana and Rhizopus oligosporus. Absidia blakesleeana produced two novel metabolites, ent-(7α, 9α)-dihydroxy-kaur-16-en-19-oic acid and ent-(1β, 7α)-dihydroxy-kaur-16-en-19-oic acid, together with three known compounds: ent-7α-hydroxy-kaur-16-en-19-oic acid, ent-(7α, 11β)-dihydroxy-kaur-16-en-19-oic acid and ent-(7α, 13)-dihydroxy-kaur-16-en-19-oic acid. The ent-7α-hydroxy-kaur-16-en-19-oic acid and ent-(7α, 9α)-dihydroxy-kaur-16-en-19-oic acid were obtained from R. oligosporus. The structures were established by spectroscopic techniques and X-ray crystallography.

Iodido(N-phenyl­thio­urea)bis­(triphenyl­phosphine)copper(I)

The coordination geometry of the Cu atom in the title compound, [CuI(C(7)H(8)N(2)S)(C(18)H(15)P)(2)], is distorted tetra-hedral; it is coordinated by two triphenyl-phosphine P atoms, one S atom from N-phenyl-thio-urea (ptu) and one I atom. The crystal structure is stabilized by intra- and inter-molecular N-H⋯I and N-H⋯S inter-actions.

TBAI/TBHP-Mediated Cascade Cyclization toward Sulfonylated Indeno[1,2-c]quinolines

Treatment of ortho-amino-substituted aryldiyne derivatives with sulfonyl hydrazides in the presence of tetrabutylammonium iodide (TBAI) and tert-butyl hydroperoxide (TBHP) led to a cascade cyclization reaction to yield sulfonylated indeno[1,2-c]quinolines in moderate to good yields. The features of the methodology include metal-free reaction, the ease of reagent handling, and a broad functional group tolerance.

N,N-Dimethyl-4-[(2-pyrid­yl)diazen­yl]aniline

The title compound, C13H14N4, adopts a trans configuration about the azo bond. There is a dihedral angle of 12.18 (7)° between the pyridine and benzene rings and the mean plane of the dimethylamino substituent is twisted by 6.1 (2)° relative to the benzene ring. In the crystal, weak intermolecular C—H⋯N hydrogen bonds result in a zigzag arrangement along [010].

Iodido[1-(propan-2-yl­idene)thio­semi­carbazide-κS]bis­(triphenyl­phosphane-κP)copper(I)

In the mononuclear title complex, [CuI(C4H9N3S)(C18H15P)2], the CuI ion displays a distorted tetrahedral coordination geometry involving two P atoms of two triphenylphosphane molecules, one S atom of a 1-(propan-2-ylidene)thiosemicarbazide molecule and one iodide ion. In the crystal, C—H⋯π interactions [C—H⋯centroid distances = 3.443 (3) and 3.788 (3) Å] and N—H⋯S hydrogen bonds form layers parallel to (100). An intramolecular N—H⋯I hydrogen bond is also observed.