Synthesis of 9-Aryl-6,6-dimethyl-5,6,7,9-tetrahydro-1,2,4-triazolo[5,1-b]quinazolin-8(4H)ones

The reaction of 3-amino-1,2,4-triazole with arylidene derivatives of dimedone and their potential synthetic equivalents leading to the formation of 9-aryl-6,6-dimethyl-5,6,7,9-tetrahydro-1,2,4-triazolo[5,1-b]quinazolin-8(4H)ones has been studied. The direction of heterocyclization has been established, and the possible mechanisms for the formation of the pyrimidine heterocycle have been analysed.     

ACTION SPECTRA FOR PHOTOTROPIC BALANCE IN Phycomyces blakesleeanus: DEPENDENCE ON REFERENCE WAVELENGTH and INTENSITY RANGE

Abstract— Action spectra for phototropic balance of Phycomyces blakesleeanus sporangiophores were measured for various reference wavelengths and intensity ranges. Balance action spectra were made at fluence rates of 10^-4 W m^-2 with reference wavelengths of 450 nm, 394 nm, 507 nm, and broadband blue light. For broad-blue light and 450 nm light as references, typical flavin-like action spectra were found with a ma jor peak at 455 nm, a secondary peak at 477 nm, and a minor peak at 383 nm; these peaks are wider for broad blue than for 450 nm light. With the 394 nm reference, there is a major peak at 455 nm, a secondary peak at 477 nm and a minor peak at 394 nm. An action spectrum with 507 nm reference has a major peak at 455 nm and a minor peak at 383 nm, but no peak at 477 nm. A balance action spectrum was made with 450 nm reference light near threshold intensity (2 times 10^-8 W m^-2); there, the 386 nm peak is greatly reduced, while the 455 nm peak is enhanced. The intensity dependence of the 386 nm peak was studied in detail for reference light of 450 nm. We found that the relative quantum efficiency of the 386 nm light increases with the logarithm of the 450 nm fluence rate; in the high intensity range (0.3 W m^-2) the relative quantum efficiency of the 386 nm light is 1.3 and approaches zero at 10^-9 W m^-2. These findings indicate that P. blakesleeanus phototropism is mediated by multiple interacting pigments or by a photochromic photoreceptor.     

Imine-enamine tautomerism of dihydroazolopyrimidines. 3. 5-Aryl-substituted 4,7(6,7)-dihydro-1,2,4-triazolo[1,5-a]pyrimidines

5-Aryl-substituted 4,7(6,7)-dihydro-1,2,4-triazolo[1,5-a]pyrimidines were obtained by condensation of 3-amino-1,2,4-triazole with -dimethylaminopropiophenone hydrochlorides or crotophenone. The effect of steric and electronic factors on the position of the imine-enamine equilibrium in solutions of the synthesized substances is examined. 5-Phenyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyriniidine was subjected to x-ray diffraction analysis.See [1] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1539–1544, November, 1991.     

Cascade cyclization reactions of 3,4,5-triamino-1,2,4-triazole with aromatic aldehydes and cycloalkanones

A three-component condensation of 3,4,5-triamino-1,2,4-triazole (1) with aromatic aldehydes 2a–f and dimedone (3) or cyclohexanone (8) afforded partially hydrogenated 9-aryl-[1,2,4]triazolo[5,1-b]quinazolin-8-ones. The structure of 2-amino-6,6-dimethyl-3-(4-nitrobenzylidene)amino-9-(4-nitrophenyl)-5,6,7,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8-one (4e) was confirmed by X-ray diffraction data. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1178–1182, July, 2006.     

GRAPHICAL ESTIMATION OF CROSS SECTIONS FROM FLUENCE-RESPONSE DATA

Abstract— Light-induced absorbance changes have been studied by several investigators as a potential assay for the blue-light receptor pigments in numerous organisms. These studies involve a flavin-mediated photoreduction of a cytochrome. Here we consider several alternative models for the photochemical kinetics linking the flavin excitation to the cytochrome absorbance change. Straightforward approximations from these models form the basis of a simple graphical procedure which, when applied to fluence-response data, leads to an estimate of the quantum efficiency for the production of the absorbance change. Such estimates are helpful in evaluating the relevance of this spectrophotometric effect to the physiological responses. Efficiencies of order unity are indicated for results on Neurospora and corn compared to a much lower efficiency for a mycelial preparation of Phycomyces.     

MODIFIED ACTION SPECTRA OF PHOTOGEOTROPIC EQUILIBRIUM IN Phycomyces blakesleeanus MUTANTS WITH DEFECTS IN GENES madA, madB, madC, and madH

Abstract— Action spectra of photogeotropic equilibrium were measured for behavioral mutants of Phycomyces blakesleeanus with defects in the genes madB, madC and madH as well as for a double mutant defective in the genes madA and madC. The action spectra of strains C109 (madB), LI (madC) and L52 (madA madC) all lack the broad near-ultraviolet peak which extends from 347 to 386 nm in the wild type; the peaks at 414 and 491 nm are also missing in these mutants. The double mutant L52 (madA madC) shows a novel broad peak at 477 nm; the relative quantum effectiveness of L52 at 477 nm is 10 times higher than in LI (madC119). These properties of the double mutant L52 (madA madC) suggest steric interaction of the madA and the madC gene products in the photoreceptor complex. For the hypertropic mutant L84 (madH) the action spectrum and absolute sensitivity are similar to those for wild type. These results confirm and extend previous findings that multiple photoreceptors are mediating phototropism in P. blakesleeanus.     

DIFFERENTIAL SPECTROPHOTOMETRY OF Phycomyces MUTANTS WITH ABNORMAL PHOTORESPONSES

Abstract— The unidentified receptor pigments responsible for phototropism and other blue light responses of Phycomyces are expected to contribute only a minuscule fraction of the in vivo absorption spectra, even for carotene-deficient ( car genotype) albino strains. The variable amount of residual carotenoids in strains with mutations in the carA gene precluded their use for the comparison of phototropism (mad) mutants with phototropically normal controls. We turned instead to carB albino strains, all of which have negligible carotene content. For various mad genes, we isolated carB mad strains by crosses and mutagenesis, and compared them with carB controls, in search of spectral differences associated with the mad photoreception defects. The spectra and their second derivatives show cytochrome bands, as well as a minor peak near 480 nm. This peak was present in carB strains, so it is probably not due to carotenoids. Strains L26 and L136 (both carB madE , but with different genetic backgrounds) showed modifications in the480–500 nm region. Sporangiophores that lacked the green material that usually interferes with in vivo spectroscopy were obtained by the addition of potassium iodide to the culture medium. Dark-grown carB sporangiophores have a more pronounced second-derivative peak at 480 nm than do light-grown sporangiophores. Growth in the light, though, did not significantly alter the spectra of sporangiophores of L131 (carB madB) or L130 (carB madC). The spectral differences may be useful in the biochemical search for the receptor pigments.