Straightforward Strategy for the Stereoselective Synthesis of Spiro-Fused (C-5)Isoxazolino- or (C-3)Pyrazolino-(C-3)quinolin-2-ones from Baylis-Hillman Adducts by 1,3-Dipolar Cycloaddition and Reductive Cyclization
作者:Virender Singh、Vijay Singh、Sanjay Batra
DOI:10.1002/ejoc.200800746
日期:2008.11
A straightforward and general approach for the stereoselective synthesis of spiro-fused (C-5)isoxazolino- or (C-3)pyrazolino-(C-3)quinolin-2-ones from the adducts offorded from the Baylis–Hillman reaction of 2-nitrobenzaldehyde and ethyl acrylate by sequential 1,3-dipolar cycloaddition and reductive cyclization is presented. It was found that the reductive cyclization of the isoxazoline derivatives
从 2 的 Baylis-Hillman 反应提供的加合物立体选择性合成螺稠合 (C-5)isoxazolino- 或 (C-3)pyrazolino-(C-3)quinolin-2-ones 的直接和通用方法-硝基苯甲醛和丙烯酸乙酯通过顺序 1,3-偶极环加成和还原环化反应。发现异恶唑啉衍生物的还原环化在 In/HCl 存在下有效进行,而吡唑啉的类似还原在 Fe/AcOH 混合物存在下进行时产生更好的产率。然而,使用 2-硝基苯甲醛和甲基乙烯基酮的 Baylis-Hillman 加合物的类似尝试没有产生所需的化合物。(© Wiley-VCH Verlag GmbH & Co. KGaA,69451 Weinheim,德国,2008 年)