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Corresponding Cis (corresponding + cis)

Distribution by Scientific Domains

Chemistry	100%

Distribution within Chemistry

General & Introductory Chemistry	50%

Selected Abstracts

Synthesis of Both Enantiomers of Conduritol C Tetraacetate and of meso -Conduritol D Tetraacetate by Oxidation of Benzoquinone Bis(ethylene acetal)

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2007
Martin Lang
Abstract Epoxidation of p -benzoquinone bis(ethylene acetal) (1) with m -chloroperbenzoic acid or hydrogen peroxide/benzonitrile afforded corresponding monoepoxide 2, which was converted into p -benzoquinone mono(ethylene acetal) monoepoxide 5 with perchloric acid. Dihydroxylation of 1 with osmium tetroxide or ruthenium trichloride/sodium periodate afforded corresponding cis -diol 6, which was subsequently acetylated to give diacetate 7. One ethyleneacetal moiety in 7 could be selectively hydrolyzed with silica gel/ferric chloride under solvent-free conditions to give ketone 8, which, upon reduction with sodium borohydride and subsequent acetylation of the formed alcohol group, afforded two diastereomeric triacetates 10. Hydrolysis of the remaining acetal functions in the two diastereomers 10, followed by reduction of the second carbonyl group as described above, afforded racemic conduritol C and meso -conduritol D tetraacetates 12 and 13, respectively. Enzymatic resolution of the racemic arabino -configured triacetate 10 with Lipozym failed, while the ribo -configured counterpart reacted smoothly to give enantiomerically pure D - ribo - and L - ribo -configured triacetates 10. The latter pair of enantiomerically pure triacetates were converted into both enantiomers of conduritol C tetraacetate 13 as described for the racemic compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Synthesis of the Spermidine Alkaloids (,)-(2R,3R)- and (,)-(2R,3S)-3-Hydroxycelacinnine: Macrocyclization with Oxirane-Ring Opening and Inversion via Cyclic Sulfamidates

HELVETICA CHIMICA ACTA, Issue 6 2003
Nikolai
The two epimers (,)- 1a and (,)- 1b of the macrocyclic lactam alkaloid 3-hydroxycelacinnine with the (2R,3R) and (2R,3S) absolute configurations, respectively, were synthesized by an alternative route involving macrocyclization with the regio- and stereoselective oxirane-ring opening by the terminal amino group (Schemes,2 and 6). Properly N -protected chiral trans -oxirane precursors provided (2R,3R)-macrocycles after a one-pot deprotection-macrocyclization step under moderate dilution (0.005,0.01M). The best yields (65,85%) were achieved with trifluoroacetyl protection. Macrocyclization of the corresponding cis -oxiranes was unsuccessful for steric reasons. Inversion at OHC(3) via nucleophilic displacement of the cyclic sulfamidate derivative with NaNO2 led to (2R,3S)-macrocycles. The synthesized (,)-(2R,3S)-3-hydroxycelacinnine ((,)- 1b) was identical to the natural alkaloid. [source]

Synthesis and Reactions of Enantiopure Substituted Benzene cis -Hexahydro-1,2-diols

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010
R. Boyd
Abstract Enantiopure cis -dihydro-1,2-diol metabolites, obtained from toluene dioxygenase-catalysed cis -dihydroxylation of six monosubstituted benzene substrates, have been converted to their corresponding cis -hexahydro-1,2-diol derivatives by catalytic hydrogenation via their cis -tetrahydro-1,2-diol intermediates. Optimal reaction conditions for total catalytic hydrogenation of the cis -dihydro-1,2-diols have been established using six heterogeneous catalysts. The relative and absolute configurations of the resulting benzene cis -hexahydro-1,2-diol products have been unequivocally established by X-ray crystallography and NMR spectroscopy. Methods have been developed to obtain enantiopure cis -hexahydro-1,2-diol diastereoisomers, to desymmetrise a meso - cis -hexahydro-1,2-diol and to synthesise 2-substituted cyclohexanols. The potential of these enantiopure cyclohexanols as chiral reagents was briefly evaluated through their application in the synthesis of two enantiomerically enriched phosphine oxides from the corresponding racemic phosphine precursors. [source]

Homogeneous [RuIII(Me3tacn)Cl3]-Catalyzed Alkene cis -Dihydroxylation with Aqueous Hydrogen Peroxide

CHEMISTRY - AN ASIAN JOURNAL, Issue 1 2008
Wing-Ping Yip Dr.
Abstract A simple and green method that uses [Ru(Me3tacn)Cl3] (1; Me3tacn=N,N,,N,,-trimethyl-1,4,7-triazacyclononane) as catalyst, aqueous H2O2 as the terminal oxidant, and Al2O3 and NaCl as additives is effective in the cis -dihydroxylation of alkenes in aqueous tert -butanol. Unfunctionalized alkenes, including cycloalkenes, aliphatic alkenes, and styrenes (14 examples) were selectively oxidized to their corresponding cis -diols in good to excellent yield (70,96,%) based on substrate conversions of up to 100,%. The preparation of cis -1,2-cycloheptanediol (119,g, 91,% yield) and cis -1,2-cyclooctanediol (128,g, 92,% yield) from cycloheptene and cyclooctene, respectively, on the 1-mol scale can be achieved by scaling up the reaction without modification. Results from Hammett correlation studies on the competitive oxidation of para -substituted styrenes (,=,0.97, R=0.988) and the detection of the cycloadduct [(Me3tacn)ClRuHO2(C8H14)]+ by ESI-MS for the 1 -catalyzed oxidation of cyclooctene to cis -1,2-cyclooctanediol are similar to those of the stoichiometric oxidation of alkenes by cis -[(Me3tacn)(CF3CO2)RuVIO2]+ through [3+2] cycloaddition (W.-P. Yip, W.-Y. Yu, N. Zhu, C.-M. Che, J. Am. Chem. Soc.2005, 127, 14239). [source]