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

作者：Yamada Ken ichi^*; Konishi Takehito; Nakano Mayu; Fujii Shintaro; Cadou Romain; Yamamoto Yasutomo; Tomioka Kiyoshi

来源：Journal of Organic Chemistry, 2012, 77(3): 1547-1553.

DOI：10.1021/jo2025042

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 (-78 to -20 degrees 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.

• 出版日期2012-2-3