Synthesis of 3-epi-6,7-dideoxyxestobergsterol A

3-Epi-6,7-dideoxyxestobergsterol A (2), an analogue of xestobergsterol A, has been synthesized from dehydroepiandrosterone (3) in 15 steps. The key synthetic intermediate, 15beta,16alpha-dioxypregn-17(20)E-ene derivative 8, was prepared from the corresponding 15beta,16beta-epoxide 6 by treating with acetic acid and titanium tetraisopropoxide. The 23-oxo side chain was constructed stereoselectively by orthoester Claisen rearrangement of 8 followed by introduction of an isobutyl group. Basic treatment of the 15,23-diketone 12 followed by deprotection gave the title compound 2.     

Steroidal glycosides from the aerial part of Asclepias incarnata L. II

Thirty new steroidal glycosides were obtained from the aerial part of Asclepias incarnata L. (Asclepiadaceae). These glycosides were confirmed to have lineolon, isolineolon, 12-O-acetyllineolon, 12-O-(Z)-cinnamoyllineolon, metaplexigenin, 15 beta-hydroxylineolon, 15 beta-hydroxyisolineolon, 16 alpha-hydroxyisolineolon, 12-O-tigloyl-16 alpha-hydroxyisolineolon as the aglycone and 2,6-dideoxyhexopyranose as the sugar sequence by spectroscopic methods and chemical evidence.     

New rearrangement in the 3-indolinone series

In an aqueous alcohol solution of hydrogen chloride 1-(2-propionylphenyl)amino-2-alkoxy-2-methyl-3-indolinone undergoes rearrangement to 2-(2-acetylcarbonyl)phenyl-3-ethylindazole. The structure of the rearrangement product was investigated by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 929–932, July, 1991.     

13CNMR-Untersuchung der Taktizit?t von Poly-(RS)tert-butyloxiran, das durch Polymerisation mit tert-C4H9OK erhalten wurde

Ohne Zusammenfassung     

Catalytic flow-injection determination of copper at nanogram levels by using color formation of N-phenyl-p-phenylenediamine with m-phenylenediamine in the presence of pyridine and ammonia as activators

A spectrophotometric flow-injection method for determining copper(II) has been developed. It is based on the catalytic effect of copper(II) on the oxidative coupling of N-phenyl-p-phenylenediamine with m-phenylenediamine in the presence of hydrogen peroxide. Pyridine and ammonia as activators increased the absorbance for the copper(II)-catalyzed coloration, and the dye formed was stabilized by adding a non-ionic surfactant. The working range of the method was 0.1-2.0 ng ml(-1) of cooper(II) with a relative standard deviation 2.4% at a sampling rate of 30 h(-1). Interference from iron(III) was effectively suppressed by citric acid. Copper in natural water samples can be determined easily.     

Synthesis and properties of fluoronitroalcohols. Report 5. 1,5-difluoro-1,1,5,5-tetranitropentan-3-ol

Conclusions 1,5-Difluoro-1,1,5,5-tetranitropentan-3-ol was obtained by reduction of 1,5-difluoro-1,1,-5, 5-tetranitropentan-3-one with NaBH₄ in the presence of BF₃ etherate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 398–401, February, 1986.