High Performance of N-Alkoxycarbonyl-imines in Triethylborane-Mediated Tin-Free Radical Addition

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• 作者：Ken-ichi Yamada ; Takehito Konishi ; Mayu Nakano ; Shintaro Fujii ; Romain Cadou ; Yasutomo Yamamoto ; Kiyoshi Tomioka
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：February 3, 2012
• 年：2012
• 卷：77
• 期：3
• 页码：1547-1553
• 全文大小：306K
• 年卷期：v.77,no.3(February 3, 2012)
• ISSN：1520-6904

文摘

Triethylborane-mediated tin-free radical alkylation of N-alkoxycarbonyl-imines, such as N-Boc-, N-Cbz-, and N-Teoc-imines, proceeded smoothly at a low temperature (鈭?8 to 鈭?0 掳C) to give the corresponding adducts in high yield. Although the formation of isocyanate was the major unfavorable reaction at room temperature, a one-pot conversion of N-Boc-imine to N-ethoxycarbonyl-adduct was possible through the corresponding isocyanate generated in situ. The higher performance of N-alkoxycarbonyl-imine than those of N-Ts- and N-PMP-imines is rationalized by a moderate electron-withdrawing character of an alkoxycarbonyl group that makes both addition of alkyl radical and trapping of the resulting aminyl radical by triethylborane efficiently fast.