- cis-1,2,3,6-Tetrahydrophthalic anhydride at 173 K
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The title compound, C8H8O1, (I), crystallizes with two nearly identical molecules in the asymmetric unit. Each molecule has a boat conformation and non-crystallographic mirror symmetry. The structure was determined in connection with a study of the possible chemical decomposition of the compound in different solvents and in contact with the atmosphere. A similar boat conformation was found in five of six structures retrieved from the Cambridge Structural Database which contain (I) as a moiety. The present structure exhibits nearly the same packing motif as the recently found monoclinic polymorph.
- Bolte, Michael,Bauch, Christian
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- Novel 1,2,3-triazole compounds: Synthesis, In vitro xanthine oxidase inhibitory activity, and molecular docking studies
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In this study, novel 1,2,3-triazole compounds containing carbasugar frameworks (5 and 6) were synthesized by the copper-catalyzed azide-alkyne cycloaddition reactions and their in vitro inhibition effects on the enzyme xanthine oxidase were investigated. All of the synthesized compounds were characterized by spectroscopic methods. According to the enzyme inhibition results, compounds 5 (IC50 = 0.586 ± 0.017 μM) and 6 (IC50 = 0.751 ± 0.021 μM) showed stronger inhibition effects than allopurinol (IC50 = 1.143 ± 0.019 μM), which is a standard drug used for inhibition of xanthine oxidase. The binding modes of the 1,2,3-triazole compounds (5 and 6) with the active site of xanthine oxidase were explained based on molecular docking studies. The molecular docking studies showed that the aromatic structure, π-π interactions and hydrophobic interactions play a major role in xanthine oxidase inhibition for compounds 5 and 6.
- Tan, Ayse
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- An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: The synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride
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In this study, we developed a new addition reaction of chlorosulfonyl isocyanate (CSI), starting from 2-ethyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione. The addition reaction of CSI with 2-ethyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione resulted in the formation of ylidenesulfamoyl chloride, whose exact configuration was determined by X-ray crystal analysis. We explain the mechanism of product formation supported by theoretical calculations.
- K?se, Aytekin,ünal, Asli,?ahin, Ertan,Bozkaya, U?ur,Kara, Yunus
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p. 931 - 936
(2019/06/08)
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- Access to amphiphilic cis-configurated polyamide-3 using alcohols as initiators
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The synthesis of polyamide-3 from 4a,5,8,8a-tetrahydro-1H-benzo[d][1,3]oxazine-2,4-dione (β-NCA, 1) using methanol, dye (Disperse Red 13), and poly(ethylene glycol) as initiator is described. The ring-opening polymerization under release of CO2 produces polyamides-3 with definite terminal groups, high purity, and relatively narrow dispersity. This route was used for preparation of block copolymers from as an example.
- Maiatska, Olga,Belkin, Alexander,Ritter, Helmut
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p. 2367 - 2369
(2015/05/13)
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- Tandem Diels-Alder/cross-coupling reactions of generated in situ organoindium reagents in a one-pot process
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[Chemical equation presented] Tandem Diels-Alder/ cross-coupling reactions with organoindium reagents generated in situ from 1-bromo-2,3-butadiene and indium were developed in a one-pot process. [4 + 2] Cycloaddition reactions using organoindium reagents and subsequent Pd-catalyzed cross-coupling reactions provided the rapid synthesis of six-membered carbocycles starting from 1-bromo-2,3-butadiene.
- Mo, Juntae,Kim, Sung Hong,Lee, Phil Ho
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supporting information; experimental part
p. 424 - 427
(2010/04/24)
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- Synthesis of diazacrown compounds with polyfunctional cyclohexane fragments
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A convenient synthetic method was developed for new diazacrown compounds that contained at polyether cavity polyfunctional cyclohexene or cyclohexane fragments of definite configuration. The synthetic procedure consists in fusion in toluene of equimolar quantities of anhydrides of 4-cyclohexene and 4,5-trans-dibromocyclohexane-cis-1,2-dicarboxylic acids with hydroxy-substituted diazacrown ether. The crown compounds synthesized under complexing conditions with AgBF4 undergo disproportionation yielding bis-crown compounds.
- Shabanov,Mamedov,Mamedov
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p. 589 - 592
(2007/10/03)
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- Improved synthesis of both enantiomers of trans-cyclohex-4-ene-1,2- dicarboxylic acid
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A facile synthesis of both enantiomers of trans-cyclohex-4-ene-1,2- dicarboxylic acid on a multigram scale, that starts from inexpensive, commercially available compounds, is described.
- Bernardi, Anna,Arosio, Daniela,Dellavecchia, Donatella,Micheli, Fabrizio
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p. 3403 - 3407
(2007/10/03)
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- Diastereoselective cis to trans desymmetrization of dimethyl succinates
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Meso-succinates, readily available by Diels-Alder cycloaddition of dimethyl maleate or maleic anhydride followed by esterification, can be isomerized quantitatively from the cis to the trans isomers in the presence of lithium alkoxides. The reaction performed with enantiopure chiral lithium alkoxides yields diastereomeric trans-succinates in good yield and selectivity.
- Michieletto, Ivan,Fabris, Fabrizio,De Lucchi, Ottorino
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p. 2505 - 2509
(2007/10/03)
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- Preparations and Crystal Structures of the 2-Oxides of Some Octahydro-3,2,1-benzoxathiazines and Octahydro-2H-3,1,2-benzoxazaphosphorines
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The cis- and trans-fused 1-benzyl-1,4,4a,5,6,7,8,8a-octahydro-3,2,1-benzoxathiazine 2-oxides and cis- and trans-fused 1-benzyl-2-phenyl-1,4,4a,5,6,7,8,8a-octahydro-2H-3,1,2-benzoxazaphosphorine 2-oxides have been prepared from the cis- and trans-2-benzylaminocyclohexanemethanols and their structures have been determined by n.m.r. and crystallographic methods.
- Goodridge, Richard J.,Hambley, Trevor W.,Ridley, Damon D.
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p. 591 - 604
(2007/10/02)
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- STEREOCHEMICAL STUDIES 83. SATURATED HETEROCYCLES 76. PREPARATION AND CONFORMATIONAL STUDY OF PARTIALLY SATURATED 3,1-BENZOXAZINES, 3,1-BENZOXAZIN-2-ONES AND 3,1-BENZOXAZINE-2-THIONES
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The cis- and trans-2-amino-4-cyclohexene-1-carboxylic acids 1 and 3 react with imidates to give the condensed-skeleton, bicyclic cis- and trans-pyrimidin-4-ones 8 and 9.The amino acids 1 and 3 were reduced to the cis- and trans-1,3-aminoalcohols 6 and 7, which were cyclized by means of imidates to the bicyclic tetrahydro-4H-3,1-benzoxazines 10 and 11, or were converted, via the corresponding carbamates 14 and 15 into the tetrahydro-4H-3,1-benzoxazin-2(1H)-ones 16 and 17.The 2-thioxo analogues 18 and 19 were prepared by cyclization of the dithiocarbamates obtained from the aminoalcohols 6 and 7 by treatment with carbon disulphide.The trans-aminoalcohol 7 and its saturated analogue reacted with p-chlorobenzaldehyde to furnish the hexahydro 13 and octahydro-4H-3,1-benzoxazine 13a, respectively. 1H and 13C NMR studies showed that, similarly to the earlier-investigated analogues containing oxygen or unsubstituted nitrogen at position 1, the synthesized cis isomers 8, 10, 16 and 18 occurred as the preferred conformer in the heterocyclic twist inverse form of N-inside type (quasiaxal C6-N bond) (B).In the trans isomers containing a saturated C-2 atom (13 and 13a), H-2 and H-6 are in cis relative positions.
- Bernath, Gabor,Stajer, Geza,Szabo, Angela E.,Fueloep, Ferenc,Sohar, Pal
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p. 1353 - 1366
(2007/10/02)
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- (Carbomethoxy)maleic Anhydride, a Highly Reactive New Dienophile and Comonomer
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(Carbomethoxy)maleic anhydride (CMA), is an extremely reactive dienophile in cycloadditions with butadiene, isoprene, and chloroprene.The second-order rate constants prove it to be more reactive than tetracyanoethylene.Diels-Alder reaction with anthracene gives the normal addition product.With cyclopentadiene, the endo adduct is obtained and with furan the exo adduct.With p-metoxystyrene, anethole, and diphenylethylene, the 2:1 Wagner-Jauregg-type adducts are obtained, while with styrene both Wagner-Jauregg and Diels-Alder ene adduct are formed.Copolymers form in certain conditions.With isobutyl and phenyl vinyl ether, an inverse-lectron-demand Diels-Alder reaction with CMA yields 2-isobutoxy- or 2-phenoxy-6-methoxy-3,4-dihydro-2H-pyran-3,4-dicarboxylic anhydride.These labile dihydropyrans revert to copolymers.
- Hall, H. K.,Nogues, P.,Rhoades, J. W.,Sentman, R. C.,Detar, M.
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p. 1451 - 1455
(2007/10/02)
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- Conformational Equilibrium in 8-Methyl-cis-2-thiahydrindane and 8-Methyl-cis-2-oxahydrindane by 13C NMR Spectroscopy
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The preferred conformation of 8-methyl-cis-thiahydrindane has been both estimated by 13C NMR chemical shifts and determined by low temperature 13C NMR spectroscopy to be the conformer with the methyl group equatorial with respect to the cyclohexane ring.This result is in disagreement with the interpretation of the temperature dependence of the CD spectra of (+) and (-) 8-methyl-cis-2-thiahydrindane, whereby the conformation with the methyl group axial with respect to the cyclohexane ring was claimed to be the preferred conformation.The preferred conformation of the related oxygen heterocycle, 8-methyl-cis-2-oxahydrindane, has been estimated by 13C NMR chemical shifts to be the conformer with the methyl group axial with respect to the cyclohexane ring.Possible reasons for these observations are discussed.
- Willer, Rodney L.
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p. 261 - 265
(2007/10/02)
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