- Synthesis of aromatic aldehydes by organocatalytic [4+2] and [3+3] cycloaddition of α,β-unsaturated aldehydes
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Organocatalytic inter- and intramolecular [4+2] and [3+3] cycloadditions of α,β-unsaturated aldehydes to give polysubstituted aromatic aldehydes are described. High periselectivity for the cycloadditions, with catalyst effects exerted by l-proline and pyrrolidine-HOAc, as well as cocatalyst, additive effects, has been observed.
- Hong, Bor-Cherng,Tseng, Hsing-Chang,Chen, Shang-Hung
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p. 2840 - 2850
(2007/10/03)
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- Formylation of Aromatic Compounds with CO in HSO3F-SbF5 under Atmospheric Pressure
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The formylation of aromatic compounds such as benzene, toluene, xylenes, mesitylene, indan, tetralin, fluorobenzene, chlorobenzene, and bromobenzene was carried out in HSO3F-SbF5 under atmospheric CO pressure at 0 deg C.In HSO3F-SbF5, both formylation and sulfonation took place to give formyl and sulfonyl compounds.In the case of alkylbenzenes, including toluene, xylenes, mesitylene, and tetralin, formylalkylbenzenesulfonyl fluorides, new compounds, were obtained by a one-pot reaction as well as alkylbenzaldehydes, alkylbenzenesulfonyl fluorides, and bis(alkylphenyl) sulfones.The direct introduction of a formyl and sulfonyl group was achieved in alkylbenzenes.The reaction path of the new compounds is a two-step reaction comprised of formylation as the first step and sulfonation as the second step.The product composition was strongly dependent on the acid strength of the HSO3F-SbF5 systems.The formyl compounds became predominant with increasing acidity of the HSO3F-SbF5 system.On the other hand, only sulfonyl compounds were produced when the acidity of the HSO3F-SbF5 system was low.
- Tanaka, Mutsuo,Iyoda, Jun,Souma, Yoshie
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p. 2677 - 2680
(2007/10/02)
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- Optically Active Spiranes, XI: Syntheses of Optically Active Mono to Heptasubstituted 5-Methyl and Ethyl-2,2'-Spirobiindanes and Related Naphthalene Derivatives of Known Chirality and Enantiomeric Purity
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Starting from optically active 5,5'-dimethyl, diethyl, and 5-ethyl-5'-methyl-2,2'-spirobiindane as well as from 5'-ethyl-spirobiindane-5-carboxylic ester of known enantiomeric purity and configuration 75 mono to polysubstituted 2,2'-spirobiindanes have been prepared.Amongst these are several compounds with rings anellated in the 6,7 (and 6',7') positions, especially a spirohydrocarbon 4x with orthogonal naphthalene units the circular dichroism of which is reported and discussed.Several mono and disubstituted 5-methyl and ethylindanes (1, 2) have been prepared as models for synthetic transformations in the spirobiindane series.From the molar rotations of symmetrically diacylated 5,5'-dimethyl and diethyl spirobiindanes (4a, 7b, 7c) empirical ligand parameters λ for acetyl and methoxycarbonyl were determined which gave much better results in the calculation of the rotations of appropriate spirobiindanes (with the "shortened polynomal Ansatz") than the λ-values deduced previously from 5,5'-disubstituted spirobiindanes.The significance of these results is briefly discussed. - Keywords: Chirality function; Circular dichroism; Ligand parameters; 5-Methyl and ethylindanes; 1H-NMR spectra
- Neudeck, Horst,Schloegl, Karl
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p. 801 - 824
(2007/10/02)
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