Complexation of enalapril maleate with b-cyclodextrin: NMR spectroscopic study in solution

A detailed NMR (1H , COSY, ROESY) spectroscopic study of complexation of enalapril maleate with b-cyclodextrin was carried out. The 1H NMR spectrum of enalapril maleate confirmed the existence of cis-trans equilibrium in solution, possibly due to hindered rotation along the amide bond. The cis-trans ratio remained almost the same in the presence of b-cyclodextrin but in one case it was found significantly different which suggests a catalytic role of b-cyclodextrin in the isomerization. 1H NMR titration studies confirmed the formation of an enalapril-b-cyclodextrin inclusion complex as evidenced by chemical shift variations in the proton resonances of both the host and the guest. The stoichiometry of the complex was determined to be 2:1 (guest: host). The mode of penetration of the guest into the b-cyclodextrin cavity as well as the structure of the complex were established using ROESY spectroscopy.

Química Nova

Print version ISSN 0100-4042

Quím. Nova vol.29 no.4 São Paulo July/Aug. 2006

Complexation of enalapril maleate with b-cyclodextrin: NMR spectroscopic study in solution

Syed Mashhood Ali*, I; Arti MaheshwariI; Fahmeena AsmatI; Mamoru KoketsuII

IDepartment of Chemistry, Aligarh Muslim University, Aligarh 202002 (UP), India
IIDivision of Instrumental Analysis, Life Science Research Center, Gifu University, Gifu, 501-1193, Japan

* e-mail:

Enalapril maleate, which exists in two geometrical forms in solution, forms a 1: 2 host-guest inclusion complex with b-CD in the concentration range studied. The aromatic ring of one guest molecule enters the b-CD cavity from narrower rim side while 5-membered ring penetrates through wider rim side as evidenced by ROESY spectrum. The structure for the complex has been proposed.

Zinc-Catalyzed Reactions of Ethenetricarboxylates with 2-(Trimethylsilylethynyl)anilines Leading to Bridged Quinoline Derivatives

Zinc-Catalyzed Reactions of Ethenetricarboxylates with
2-(Trimethylsilylethynyl)anilines Leading to Bridged Quinoline Derivatives

Shoko Yamazaki, Satoshi Morikawa, Kazuya Miyazaki, Masachika Takebayashi
Yuko Yamamoto, Tsumoru Morimoto, Kiyomi Kakiuchi, Yuji Mikata
Org. Lett. 2009, 11,13, 2796-2799.

Highlighted in .
ChemInform 2009, 40(46)

Zinc Lewis acid-catalyzed cyclization of ethenetricarboxylate derivatives 1 with 2-ethynylanilines has been examined. Reaction of 1,1-diethyl 2-tert-butyl ethenetricarboxylate1b with 2-(trimethylsilylethynyl)aniline substrates in the presence of Zn(OTf)2 gave bridged quinoline derivatives in 43−85% yield. The reaction of 1b with 2′-aminoacetophenone also gave the bridged quinoline derivative in 41% yield. Thermal reaction of bridged quinolines (180−190 °C) afforded indole derivatives in moderate to good yields.


Chemical structure of prismane

650-42-0 cas


Prismane is a polycyclic hydrocarbon with the formula C6H6. It is an isomer of benzene, specifically a valence isomer. Prismane is far less stable than benzene. The carbon (and hydrogen) atoms of the prismane molecule are arranged in the shape of a six-atomtriangular prismAlbert Ladenburg proposed this structure for the compound now known as benzene.[1] The compound was not synthesized until 1973.[2]
Chemical structure of prismane Chemical structure of prismane
CPK model of prismane
CAS number 650-42-0 
ChemSpider 16736515 Yes
Jmol-3D images Image 1
Molecular formula C6H6
Molar mass 78.11 g mol−1


In the mid 19th century, investigators proposed several possible structures for benzene which were consistent with its empirical formula, C6H6, which had been determined by combustion analysis. The first, which was proposed by Kekulé in 1867, later proved to be closest to the true structure of benzene. This structure inspired several others to propose structures that were consistent with benzene’s empirical formula; for example, Ladenburg proposed prismane, Dewar proposed Dewar benzene, and Koerner and Claus proposedClaus’ benzene. Some of these structures would be synthesized in the following years. Prismane, like the other proposed structures for benzene, is still often cited in the literature, because it is part of the historical struggle toward understanding the mesomeric structures and resonance of benzene. Some computational chemists still research the differences between the possible isomers of C6H6.[3]


Prismane is a colourless liquid at room temperature. The deviation of the carbon-carbon bond angle from 109° to 60° in a triangle leads to a high ring strain, reminiscent of that of cyclopropane but greater. The compound is explosive, which is unusual for a hydrocarbon. Due to this ring strain, the bonds have a low bond energy and break at a low activation energy, which makes synthesis of the molecule difficult; Woodward and Hoffmann noted that prismane’s thermal rearrangement to benzene is symmetry-forbidden, comparing it to “an angry tiger unable to break out of a paper cage.”[4]

The substituted derivative hexamethylprismane (in which all six hydrogens are substituted by methyl groups) has a higher stability, and was synthesized by rearrangement reactionsin 1966.[5]


Synthesis of Prismane

The synthesis starts from benzvalene (1) and 4-phenyltriazolidone, which is a strong dienophile. The reaction is a stepwise Diels-Alder like reaction, forming a carbocation as intermediate. The adduct (2) is then hydrolyzed under basic conditions and afterwards transformed into a copper(II) chloride derivative with acidic copper(II) chloride. Neutralized with a strong base, the azo compound (3) could be crystallized with 65% yield. The last step is a photolysis of the azo compound. This photolysis leads to a biradical which forms prismane (4) and nitrogen with a yield of less than 10%. The compound was isolated by preparative gas chromatography.


Chemical structure
MeLi, CH2Cl2, 
-45 °C, 45 %
Chemical structure


Chemical structure

Et2O, Dioxane
0 °C to RT, 60 min, 50-60 %

Chemical structure
Reflux, 24 h
Chemical structure
CuCl2, HCl,
65 % (2 steps)
Chemical structure
30 °C, 5 h, 8 %
Chemical structure


  1. Ladenburg A. (1869). “Bemerkungen zur aromatischen Theorie“. Chemische Berichte 2: 140–2. doi:10.1002/cber.18690020171.
  2. Katz T. J., Acton N. (1973). “Synthesis of Prismane”. Journal of the American Chemical Society 95 (8): 2738–2739. doi:10.1021/ja00789a084.
  3.  UD Priyakumar, TC Dinadayalane, GN Sastry (2002). “A computational study of the valence isomers of benzene and their group V hetero analogs”New J. Chem. 26 (3): 347–353.doi:10.1039/b109067d.
  4. R. B. Woodward and R. Hoffmann, Angew. Chem., Int. Ed. Engl.8, 789, (1969)
  5.  Lemal D. M., Lokensgard J. P. (1966). “Hexamethylprismane”. Journal of the American Chemical Society 88 (24): pp 5934–5935. doi:10.1021/ja00976a046.

Fermentation of hydrolysate detoxified by pervaporation through block copolymer membranes

Graphical abstract: Fermentation of hydrolysate detoxified by pervaporation through block copolymer membranes

Fermentation of hydrolysate detoxified by pervaporation through block copolymer membranes


The large-scale use of lignocellulosic hydrolysate as a fermentation broth has been impeded due to its high concentration of organic inhibitors to fermentation. In this study, pervaporation with polystyrene-block-polydimethylsiloxane-block-polystyrene (SDS) block copolymer membranes was shown to be an effective method for separating volatile inhibitors from dilute acid pretreated hydrolysate, thus detoxifying hydrolysate for subsequent fermentation. We report the separation of inhibitors from hydrolysate thermodynamically and quantitatively by detailing their concentrations in the hydrolysate before and after detoxification by pervaporation. Specifically, we report >99% removal of furfural and 27% removal of acetic acid with this method. Additionally, we quantitatively report that the membrane is selective for organic inhibitor compounds over water, despite water’s smaller molecular size. Because its inhibitors were removed but its sugars left intact, pervaporation-detoxified hydrolysate was suitable for fermentation. In our fermentation experiments, Saccharomyces cerevisiae strain SA-1 consumed the glucose in pervaporation-detoxified hydrolysate, producing ethanol. In contrast, under the same conditions, a control hydrolysate was unsuitable for fermentation; no ethanol was produced and no glucose was consumed. This work demonstrates progress toward economical lignocellulosic hydrolysate fermentation.



Corresponding authors
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, USA 
E-mail: ;
Tel: +1 (510) 642-8937
Department of Bioengineering, University of California, Berkeley, USA 
E-mail: ;
Tel: +1 (510) 643-5678
Energy Biosciences Institute, University of California, Berkeley, USA
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, USA
Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, USA
Green Chem., 2014, Advance Article

DOI: 10.1039/C4GC00756E











Received 28 Apr 2014, Accepted 24 Jun 2014
First published online 11 Jul 2014

Hydrolysate was pervaporated with a block copolymer membrane, removing inhibitors but leaving sugars, creating a viable fermentation broth.





A two-step tandem reaction to prepare hydroxamic acids directly from alcohols – Organic & Biomolecular Chemistry (RSC Publishing) //

*Corresponding authors
aDipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari, Italy
Org. Biomol. Chem., 2014,12, 4582-4585

DOI: 10.1039/C4OB00693C!divAbstract

Efficient and selective copper-catalyzed organic solvent-free and biphasic oxidation of aromatic gem-disubstituted alkenes to carbonyl compounds by tert-butyl hydroperoxide at room temperature

Efficient and selective copper-catalyzed organic solvent-free and biphasic oxidation of aromatic gem-disubstituted alkenes to carbonyl compounds by tert-butyl hydroperoxide at room temperature

Green Chem., 2014, 16,3013-3017
DOI: 10.1039/C3GC42624F, Communication
Md. Munkir Hossain, Wei-Kai Huang, Hung-Jie Chen, Pei-Han Wang, Shin-Guang Shyu
Biphasic Cu(II) catalyzed selective oxidative cleavage of aromatic gem-disubstituted alkenes to carbonyl compounds using tert-butyl hydroperoxide at room temperature.
Copper-catalyzed alkene oxidation to carbonyl compounds by tert-butyl hydroperoxide (TBHP) under organic solvent-free and biphasic conditions at room temperature is selective for the aromatic gem-disubstituted alkenes. Enhanced reactivity was observed in the presence of 2,9-dimethyl-1,10-phenanthroline (neocuproine). The reaction is economically attractive because the yield is high, and separation of products and recycling of the catalyst are easy.



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