A Direct Retro-Reformatsky Fragmentation: Formal Ring Enlargement of Cyclic Ketones for Novel and Practical Synthesis of Heterocyclic Enamines
作者:Mei-Xin Zhao、Mei-Xiang Wang、Chu-Yi Yu、Zhi-Tang Huang、George W. J. Fleet
DOI:10.1021/jo0351320
日期:2004.2.1
developed from the formal ring enlargement of cyclic ketones, which comprised the retro-Reformatsky fragmentation reaction as a key step. Under alkaline bromination conditions, the Reformatsky adducts derived from five- to seven-membered cyclic ketones underwent efficiently a direct retro-Reformatsky fragmentation, followed by spontaneous α,α-dibromination, to produce α,α,ω-tribromo-β-ketoester compounds
从环酮的正式环扩大已经开发出一种新颖而实用的杂环烯胺的合成方法,其中包括Retro-Reformatsky裂解反应是关键步骤。在碱性溴化条件下,由五元至七元环状酮衍生的Reformatsky加合物有效地进行了直接Retro-Reformatsky裂解,然后自发进行α,α-二溴化,生成α,α,ω-三溴-β-酮酸酯化合物一锅反应。在温和的条件下用Cu-Zn合金高度区域选择性地还原α,α,ω-三溴-β-酮酸酯,得到的ω-溴-β-酮酸酯的产率高至优异。用叠氮化钠处理ω-溴-β-酮酸酯,然后进行分子内氮杂-维蒂希反应或催化加氢提供杂环仲烯胺,