2008年
Highly enantio- and s-trans C = C bond selective catalytic hydrogenation of cyclic enones: Alternative synthesis of (-)-menthol
CHEMISTRY-A EUROPEAN JOURNAL
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- 巻
- 14
- 号
- 7
- 開始ページ
- 2060
- 終了ページ
- 2066
- 記述言語
- 英語
- 掲載種別
- DOI
- 10.1002/chem.200701505
- 出版者・発行元
- WILEY-V C H VERLAG GMBH
A highly enantioselective catalytic hydrogenation of cyclic enones was achieved by using the combination of a cationic Rh-I complex, (S)5,5'-bis{di(3,5-di-tert-butyl-4-methoxyphenylphosphino)}-4,4'-bi-1,3-benzodioxole (DTBM-SEGPHOS), and (CH2CH2PPh3Br)(2), The presence of an s-cis C=C bond isopropylidene moiety on the cyclic enone influenced the enantioselectivity of the hydrogenation. Thus, the hydrogenation of 3-alkyl-6-isopropylidene-2-cyclohexen-1-one, which contains both s-cis and s-trans enones, proceeded in excellent enantioselectivity (up to 98% ee). To obtain high enantio- and s-trans selectivities, the addition of a halogen source to the cationic Rh complex was the essential step. With the key step of the s-trans selective asymmetric hydrogenation of piperitenone, we demonstrated a new synthetic method for optically pure (-)-menthol via three atom-economical hydrogenations. Moreover, we found that the complete s-trans and s-cis C=C bond selective reactions were also realized by the proper choice of both the chiral ligands and halides.
- リンク情報
- ID情報
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- DOI : 10.1002/chem.200701505
- ISSN : 0947-6539
- eISSN : 1521-3765
- Web of Science ID : WOS:000253932900007