Synthesis and Application of Novel Chiral 1,2-Diaryl Compounds bearing Pentafluorophenyl Group.
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Accession number;02A0620430
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| Title;Synthesis and Application of Novel Chiral 1,2-Diaryl Compounds bearing Pentafluorophenyl Group. |
| Author;
SAKAI T
(Okayama Univ., Okayama, Jpn)
TANAKA H
(Okayama Univ., Okayama, Jpn)
ISHIDA T
(Okayama Univ., Okayama, Jpn)
MINAMI S
(Okayama Univ., Okayama, Jpn)
EMA T
(Okayama Univ., Okayama, Jpn)
KORENAGA T
(Okayama Univ., Okayama, Jpn)
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Journal Title;Fusso Kagaku Toronkai Koen Yoshishu
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Journal Code:F0135B
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ISSN:
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VOL.25th;NO.;PAGE.81(2001)
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| Figure&Table&Reference; |
| Pub. Country;Japan |
| Language;English |
| Abstract;Pentafluorophenyl group has unique properties such as stacking ability with aromatic ring and strong electoron-withdrawing properties. We have been studying on the introduction of the pentafluorophenyl group(s) into 1,2-ethanediols, .ALPHA.-amino alcohols and 1,2-ethanediamines, aiming to enhance the reactivity and selectivity as chiral ligands in asymmetric syntheses, as compared with the known phenyl derivatives. In these aspects, optically pure compounds have been synthesized so far. Here we report the details of the preparations and their applications to some asymmetric syntheses. Diols were transformed to the corresponding dioxaborolanes, whose structures were analyzed by 1H and 19F NMR. spectra. Mono(pentafluorophenyl) amino alcohols was transformed to the corresponding oxazaborolidine which was used in the asymmetric reduction of acetophenone. We found that the oxazaborolidine from Mono(pentafluorophenyl) amino alcohols worked as a asymmetric catalyst to give optically active phenethylalcohol as shown below, where ee(s) were improved as raising the temperatures, as expected from the results using phenyl derivative. In addition, diamine was effectively applied in the Noyori's BINAP-Ru/diamine catalyst, causing hydrogenation of acetophenone to give alcohol in 100% conv. with improved ee of 92% (non fluorinated isomer 83%ee). (author abst.) |
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