Divergent Chemical Synthesis of Prolines Bearing Fluorinated One-Carbon Units at the 4-Position via Nucleophilic 5-Endo-Trig Cyclizations

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• 作者：Ryo Nadano ; Yu Iwai ; Takashi Mori ; Junji Ichikawa
• 刊名：Journal of Organic Chemistry
• 出版年：2006
• 出版时间：November 10, 2006
• 年：2006
• 卷：71
• 期：23
• 页码：8748 - 8754
• 全文大小：137K
• 年卷期：v.71,no.23(November 10, 2006)
• ISSN：1520-6904

文摘

N-[3-(Trifluoromethyl)homoallyl]sulfonamides, prepared via ring opening of (S)-glycidyl ethers or2-aryloxiranes with 1-(trifluoromethyl)vinyllithium, underwent intramolecular addition or S_N2'-type reactionin the normally disfavored 5-endo-trig fashion, leading to 2-substituted 4-(trifluoromethyl)- or 4-(difluoromethylene)pyrrolidines. Both - and -face-selective hydrogenation of the 4-difluoromethylenegroup afforded syn- and anti-4-(difluoromethyl)pyrrolidines, respectively. These sequences, followed bythe oxidation of a 2-hydroxymethyl or 2-aryl group, successfully provided prolines with a trifluoromethyl,difluoromethylene, or difluoromethyl group at the 4-position, including optically active prolines.