Synthesis of 2,24-Diepicastasterone and 3,24-Diepicastasterone as Potential Brassinosteroid Metabolites of the Cockroach Periplaneta americana

2002 ◽  
Vol 67 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Brunhilde Voigt ◽  
Andrea Porzel ◽  
Günter Adam ◽  
Dieter Golsch ◽  
Waldemar Adam ◽  
...  
Keyword(s):  
Periplaneta Americana ◽  
Reference Standards ◽  
Water Addition ◽  
X Ray ◽  
Epoxy Derivative ◽  
Metabolic Conversion ◽  
Acid Catalyzed

Investigations of the metabolic conversion of the phytohormone 24-epicastasterone (1) in the cockroach Periplaneta americana (L.) required the synthesis of 2,24-diepicastasterone (4), 3,24-diepicastasterone (7b) and 2-dehydro-3,24-diepicastasterone (9) as reference standards. 2,24-Diepicastasterone (4) was synthesized from 2α,3α-epoxy derivative 2 as well as from the 2β,3β-epoxy-22,23-diol 3 by acid-catalyzed water addition to the epoxy function leading to the desired 2β,3α-trans functionality. 3,24-Diepicastasterone (7b) was prepared by NaBH4-reduction of the 3-oxo derivative 6. Upon deprotection conditions from the ketol acetonides 6 and 8 in both cases 2-dehydro-3,24-diepicastasterone (9) was obtained. The structure of 2,24-diepicastasterone (4) was confirmed by X-ray analysis.

Evaluation of Geochemical Reference Standards by X-Ray Fluorescence Analysis

1987 ◽  
Vol 11 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Allen L. Stork ◽  
David K. Smith ◽  
James B. Gill
Keyword(s):  
Fluorescence Analysis ◽  
Reference Standards ◽  
X Ray

The photoaddition of 1,3-diketonatoboron difluorides with benzene derivatives

1991 ◽  
Vol 69 (3) ◽  
pp. 423-431 ◽  
Author(s):  
Yuan L. Chow ◽  
Xinxin Ouyang
Keyword(s):  
Crystallographic Analysis ◽  
Secondary Oxidation ◽  
Enol Ethers ◽  
X Ray ◽  
Thermal Reactions ◽  
Secondary Reactions ◽  
Enol Acetates ◽  
Orthogonal Orientation ◽  
Acid Catalyzed ◽  
Boron Difluoride

The boron difluoride complexes of 2-acetylcyclohexanone, 2-acetylcyclopentanone, and acetylacetone (abbreviated as ACHBF2, ACPBF2, and AABF2) were irradiated in the presence of benzene to give the 1:1 adducts as the primary photoadducts; for certain BF2 complexes, toluene, chlorobenzene, benzonitrile, and methyl benzoate were also used as substrates. The 1,5-diketone photoadducts were assumed to form by a [2+2] photocycloaddition followed by cyclobutane opening and hydrolysis to give 1,2 adducts. They undergo a variety of secondary thermal reactions, probably acid catalyzed, to give enol ethers, enol acetates, acetophenones, and ketonylacetophenones. The efficiency of these secondary reactions determines the final products. Photoaddition with a monosubstituted benzene preferentially occurs at the 3,4 bond without regioselectivity. Under oxygen, ACHBF2 photolytically reacts with benzene to give a secondary oxidation product of a 10-membered cyclic alkylphe-none, which is proven by X-ray crystallographic analysis to have the benzene ring and carbonyl group in orthogonal orientation. It is shown that the singlet excited state ACHBF2 initiates the photoaddition, probably through the formation of the benzene exciplex, which could be detected by its emission. While the Stern–Volmer rates are small, the quantum yield of photoaddition products is as high as 0.12–0.19 under limiting conditions. Key words: [2+2] photocycloaddition, non-planar alkanophenone, macrocyclic alkanophenone, boron difluoride complexes, photoaddition to benzenes.

Studies on Crop Function in the Cockroach (Periplaneta Americana L.)

1963 ◽  
Vol 40 (4) ◽  
pp. 763-773
Author(s):  
K. G. DAVEY ◽  
J. E. TREHERNE
Keyword(s):  
Mode Of Action ◽  
Periplaneta Americana ◽  
Methyl Cellulose ◽  
X Ray ◽  
A Minor

1. The structure and mode of action of the proventriculus are described. 2. X-ray photographs have shown that as the crop empties the decrease in volume of the fluid is partially compensated for by the swallowing of air. 3. The effects of various factors upon the rate of crop-emptying have been studied using solutions of different osmotic pressures. Changes in viscosity, effected by the addition of methyl cellulose, produce only a minor reduction in crop-emptying. The frequency of opening of the proventricular valve is not proportional to the rate of crop-emptying over the whole range of concentrations used, and it is assumed that changes in other parameters must affect the process.

scholarly journals Indene dimerization products

2002 ◽  
Vol 67 (6) ◽  
pp. 393-406 ◽  
Author(s):  
Jovan Jovanovic ◽  
Michael Spiteller ◽  
Wilhelm Elling
Keyword(s):  
Molecular Weight ◽  
X Ray ◽  
Alkylation Product ◽  
The Third ◽  
Product Mixture ◽  
Acid Catalyzed ◽  
Model Substances ◽  
Pyrolysis Oils

The reaction of 1H-indene (indene) in the presence of Friedel-Crafts acids was studied. As expected [M. Spiteller, J. Jovanovic, Fuel 78(1999)1263] there were dimers and trimers in the product mixture together with higher oligomers. Among products with double molecular weight relative to the molecular weight of indene, the structure of four compounds was determined: 6-(2?,3?-dihydro-1?H-inden-1?-yl)-1H-indene 2-(2?,3?-dihydro-1?H-inden-1?-yl)-1H-indene 1-(2?,3?-dihydro-1?H-inden-2?-yl)-1H-indene and 2,3,1?,3?-tetrahydro-[1,2?]biindenylidene. It was shown that the first one represents an indene alkylation product and that the others were obtained by bonding of the indan-1-ylium ion and indene at the position 2, followed by acid catalyzed 1,2-hydride rearrangement in the case of the third and fourth one. Considering the indene dimerization products as components of pyrolysis oils and as interesting compounds to be used as model substances for NMR, MS and X-ray analysis, the reaction, separation and isolation parameters were optimized in this study.

X-ray diffraction has limited applicability in investigation of milk tampering

2019 ◽  
Vol 86 (3) ◽  
pp. 337-340
Author(s):  
Ana Paula Pavão Battaglini ◽  
Alexandre Urbano ◽  
Vanerli Beloti ◽  
Edson Antonio Rios ◽  
Juliana Ramos Pereira ◽  
...  
Keyword(s):  
Sodium Citrate ◽  
Freezing Point ◽  
Raw Milk ◽  
Physicochemical Analysis ◽  
Crystallographic Analysis ◽  
X Ray Diffraction ◽  
Water Addition ◽  
X Ray ◽  
Freeze Dried ◽  
Limited Applicability

AbstractThe aim of this work was to use X-ray diffraction to identify substances used for adulteration of raw milk and to determine if crystallographic analysis can detect extraneous substances in milk. Two unknown substances were sent anonymously by employers linked to the dairy chain, who claimed that they were added directly in milk prior to water addition by truck drivers. The samples were analyzed by X-ray diffraction and submitted to physicochemical analysis. The first substance was identified by X-ray diffraction as sodium citrate, complying with its physicochemical attributes, such as the powerful ability to decrease the freezing point. The second substance was identified by X-ray diffraction as sucrose and this result was also in agreement with its ability to increase the density, decrease the freezing point and finally, to be positive for sucrose in the resorcinol qualitative test. To evaluate if X-ray diffraction can detect extraneous substances already mixed in milk, fresh raw milk samples tampered with urea, sodium hydroxide, sodium citrate and sucrose were freeze dried and analyzed by X-ray diffraction, with no detection of any extraneous substances at any percentage. This is the first report of attempted diagnosis of extraneous substances in milk by X-ray diffraction. However, this technique can be useful only when applied to identify substances used for adulteration prior to its dilution in milk, since the amorphous nature of milk seems to be a limitation for the accurate detection of extraneous substances.

Acid-catalyzed cyclization of 3,3',4,4'-tetrahydro-1,1'-binaphthyl and single-crystal x-ray structure determination of a polycyclic stable ozonide

1984 ◽  
Vol 49 (6) ◽  
pp. 1030-1033 ◽  
Author(s):  
Thomas K. Dobbs ◽  
Arnold R. Taylor ◽  
Julie A. Barnes ◽  
Belma D. Iscimenler ◽  
Elizabeth M. Holt ◽  
...  
Keyword(s):  
Single Crystal ◽  
Structure Determination ◽  
X Ray ◽  
Acid Catalyzed
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