Synthetic analogs of natural flavolignans. V. A new synthesis of 6-halogeno-1,3-benzodioxane analogs of silandrin and hydnocarpin

6-Halogeno-1,3-benzodioxane analogs of chalcones have been synthesized by various methods. Flavanone and flavone analogs of silandrin and hydnocarpin have been obtained from them. The structures of the new flavonoids have been shown by their PMR spectra.     

Modified Coumarins. 9. Synthesis of Amino-Acid Derivatives of 3-(2,3,5-Trimethyl-7-oxofuro[3,2-g]chromen-6-yl)propanoic Acid

Furocoumarins modified by amino acids were prepared by condensation of the N-hydroxysuccinimide ester of 3-(2,3,5-trimethyl-7-oxofuro[3,2-g]chromen-6-yl)propanoic acid with amino acids.     

UP-conversion of terahertz radiation induced by photon drag effect

An all-optical approach to convert terahertz radiation (THz, wavelength λ₁) into infrared (IR, peak wavelength λ₂) is presented. We show that this up-conversion process is due to the photon drag effect induced by the THz radiation in intrinsic narrow-gap semiconductors followed by spatial redistribution of current carriers and band-to-band radiative recombination. The process results in non-selective high-speed (ns range rise/fall times) IR imaging of positive (conventional luminescence) and/or negative (negative luminescence) contrasts. Estimates made for an InSb pixelless converter at 300 K and moderate THz intensity (kW/cm²) show that this up-conversion process (with λ₁/λ₂>10²) can be observed with a conventional thermal imaging camera.     

Rigidity of Branch Groups Acting on Rooted Trees

Automorphisms of groups acting faithfully on rooted trees are studied. We find conditions under which every automorphism of such a group is induced by a conjugation from the full automorphism group of the rooted tree. These results are applied to known examples such as Grigorchuk groups, Gupta–Sidki group, etc.     

Synthetic and modified isoflavonoids V. Synthesis of 2-trifluoromethyl-substituted analogues of pseudobaptigenin

New two-trifluoromethylchromones with 1,3-benzodioxole and 1,4-benzodioxane nuclei in position 3 have been synthesized. Taras Shevchenko Kiev University KIEN. Karakalpak Division, Uzbekistan Academy of Sciences, Nukus. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 820–822, November–December, 1993.     

Spectral Properties of Image Measures Under the Infinite Conflict Interaction

We introduce the conflict interaction with two positions between a couple of image probability measures and consider the associated dynamical system. We prove the existence of invariant limiting measures and find the criteria for these measures to be a pure point, absolutely continuous, or singular cotinuous as well as to have any topological type and arbitary Hausdorff dimension.     

Mixed anhydride of acetic and formic acids in the synthesis of chromones

A study was carried out on the reaction of -substituted 2-hydroxyacetophenones with the mixed anhydride of acetic and formic acids in the presence of bases of different strength. Chromones containing a conjugated electron-withdrawing substituent at C₍₃₎ are formed in close to quantitative yield in the presence of triethylamine. The preparation of chromones containing an unconjugated substituent under these conditions is recommended only for 5-hydroxy chromones.For Communication 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 595–600, May, 1992     

Amino acid derivatives of 2-R-7-hydroxy-3′,4′-ethylenedioxyisoflavones

A number of 7-O-aminoacyl derivatives of isoflavones have been obtained by the interaction of 2-R-7-hydroxy-3,4-ethylenedioxyisoflavones with the symmetrical anhydrides of N-protected amino acids.Kiev Tara Shevshenko University, Ukraine, 252033, Kiev, Ul. Vladimirskaya, 64, tel./fax 225-12-73. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 334–338, May–June, 1999.     

Synthetic analogs of natural flavolignans. V. A new synthesis of 6-halogeno-1,3-benzodioxane analogs of silandrin and hydnocarpin

6-Halogeno-1,3-benzodioxane analogs of chalcones have been synthesized by various methods. Flavanone and flavone analogs of silandrin and hydnocarpin have been obtained from them. The structures of the new flavonoids have been shown by their PMR spectra.KIEN Karakalpak Division, Academy of Sciences of the Republic of Uzbekistan, Nukus. Taras Shevchenko Kiev University, Ukraine. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 494–498, July–August, 1994.     

3-Furylchromones

-[2-(5-Methoxycarbonyl)furyl]-2,4-dihydroxy- and 2,4,6-trihydroxyacetophenones were obtained by the condensation of polyphenols with (2-methoxycarbonyl-5-furyl)acetonitrile. 7-Acetoxy- and 5,7-diacetoxy-2-methyl-3-[2-(5-methoxycarbonyl)furyl]chromones were obtained from them by reaction with acetic anhydride in the presence of triethylamine and were subsequently deacylated to 7-hydroxy and 5,7-dihydroxy compounds. 7-Hydroxy- and 5,7-dihydroxy-2-ethoxycarbonyl-3-[2-(5-methoxycarbonyl)furyl]chromones were obtained from the indicated acetophenones by reaction with ethoxalyl chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1317–1320, October, 1972.