Synthesis of Nonracemic 1,4-Benzoxazines via Ring Opening/Cyclization of Activated Aziridines with 2-Halophenols: Formal Synthesis of Levofloxacin
作者:Abhijit Mal、Imtiyaz Ahmad Wani、Gaurav Goswami、Manas K. Ghorai
DOI:10.1021/acs.joc.8b00788
日期:2018.8.3
under one-pot conditions to furnish the 3,4-dihydro-1,4-benzoxazine derivatives in excellent yields (up to 95%). The strategy offers a short and efficient synthesis to (S)-3-methyl-1,4-benzoxazine (S)-3v, a late stage intermediate in the synthesis of levofloxacin.
已经通过一种有效且简单的方法以优异的对映体和非对映体特异性(ee> 99%,de> 99%)合成了新型3,4-二氢-1,4-苯并恶嗪衍生物。反应通过路易斯酸催化活化氮丙啶与2-卤代苯酚的S N 2型开环,然后在一锅条件下逐步进行Cu(I)催化的分子内C–N环化以提供3,4。 -二氢-1,4-苯并恶嗪衍生物,收率极高(高达95%)。该策略提供了短而有效的合成(S)-3-甲基-1,4-苯并恶嗪(S)-3v的方法,后者是左氧氟沙星合成的后期中间体。