- Remote ester group leads to efficient kinetic resolution of racemic aliphatic alcohols via asymmetric hydrogenation
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A highly efficient method for kinetic resolution of racemic aliphatic alcohols without conversion of the hydroxyl group has been realized; the method involves hydrogenation mediated by a remote ester group and is catalyzed by a chiral iridium complex. This powerful, environmentally friendly method provides chiral δ-alkyl-δ-hydroxy esters and δ-alkyl-1,5-diols in good yields with high enantioselectivities even at extremely low catalyst loading (0.001 mol %).
- Yang, Xiao-Hui,Wang, Ke,Zhu, Shou-Fei,Xie, Jian-Hua,Zhou, Qi-Lin
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p. 17426 - 17429
(2015/02/02)
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- Asymmetric synthetic study of macrolactin analogues
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We designed two aromatic analogues 1a and 1b of macrolactin A with expectation of enhancing biological activity and metabolical stability. As a result of retrosynthetic analysis of these compounds 1a-b, two synthetic strategies have been examined. The first strategy includes the enantioselective addition of nonadienyl anion, derived from 3, to aldehyde 4 as a key step. The second one includes epimerization of ynone 7 to (E,E)-conjugated dienone 31 and subsequent diastereoselective hydride-reduction of 31. Although the former route furnished no desired target, the latter one was revealed to work well for the synthesis of 1. Unfortunately, the aimed (2Z,4E)-analogue 1a could not be synthesized due to an epimerization of the (2Z)-olefin into the (2E)-olefin. However, these methods could be applied to the total asymmetric synthesis of the (2E,4E)-analogue 1b. Overall, control of all of the four stereocenters was achieved by means of asymmetric and diastereoselective reactions without using any chiral natural sources.
- Kobayashi, Yusuke,Fukuda, Akihiro,Kimachi, Tetsutaro,Ju-ichi, Motoharu,Takemoto, Yoshiji
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p. 2607 - 2622
(2007/10/03)
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