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[摘要]:A series of 5-difluoromethyl-isoxazoles 2 were prepared, and their regioselective nucleophilic addition to aldehydes was investigated. It was found that the nucleophilic difluoromethylation of aldehydes with 5-difluoromethyl-isoxazoles could be efficiently and uniquely achieved in the presence of LDA as a base that provides a large steric hindrance. In contrast, 3,4,5-trisubstituted 5-difluoromethyl isoxazoles were alternatively afforded as the sole product in moderate yields when n-BuLi was used as the base. (c) 2012 Elsevier B.V. All rights reserved. |
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