Liu Feng, Liu Kun, Yuan Xinting, Li Chaozhong
Joint Laboratory of Green Synthetic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, People's Republic of China.
J Org Chem. 2007 Dec 21;72(26):10231-4. doi: 10.1021/jo7015967. Epub 2007 Nov 15.
The cyclization of neutral primary pent-4-enylaminyl radicals was investigated experimentally and theoretically. Unlike the corresponding secondary aminyl radicals, primary pent-4-enylaminyl radicals underwent efficient cyclization to afford the pyrrolidine and/or piperidine products in good to high yields. While the simple pent-4-enylaminyl radical gave predominately the 5-exo cyclization product, 4-chloropent-4-enylaminyl radicals led to the formation of the corresponding 6-endo cyclization products in excellent regioselectivity. Theoretical calculations revealed that the 5-exo cyclization rate of primary aminyl radicals is about 3-4 orders of magnitude higher than that of secondary aminyl radicals.
对中性伯戊-4-烯基氨基自由基的环化反应进行了实验和理论研究。与相应的仲氨基自由基不同，伯戊-4-烯基氨基自由基能高效环化，以良好至高产率得到吡咯烷和/或哌啶产物。虽然简单的戊-4-烯基氨基自由基主要生成5-外向环化产物，但4-氯戊-4-烯基氨基自由基能以优异的区域选择性生成相应的6-内向环化产物。理论计算表明，伯氨基自由基的5-外向环化速率比仲氨基自由基高约3-4个数量级。
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