Gillis Eric P, Burke Martin D
Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
J Am Chem Soc. 2008 Oct 29;130(43):14084-5. doi: 10.1021/ja8063759. Epub 2008 Oct 7.
Due to its sensitivity to most synthetic reagents, it is typically necessary to introduce the boronic acid functional group just prior to its utilization. Overcoming this important limitation, we herein report that air- and chromatographically stable MIDA boronates are compatible with a wide range of common reagents which enables the multistep synthesis of complex boronic acid building blocks from simple B-containing starting materials. X-ray and variable temperature NMR studies link the unique stability of MIDA boronates to a kinetic inaccessibility of the potentially reactive boron p-orbital and/or nitrogen lone pair. These findings were collectively harnessed to achieve a short and modular total synthesis of (+)-crocacin C via the iterative cross-coupling of a structurally complex, MIDA-protected haloboronic acid building block.
由于其对大多数合成试剂敏感，通常需要在使用前引入硼酸官能团。为克服这一重要限制，我们在此报告，对空气和色谱稳定的MIDA硼酸酯与多种常见试剂兼容，这使得能够从简单的含硼起始原料多步合成复杂的硼酸结构单元。X射线和变温核磁共振研究表明，MIDA硼酸酯的独特稳定性与潜在反应性硼p轨道和/或氮孤对的动力学不可及性有关。这些发现被共同用于通过结构复杂的、MIDA保护的卤代硼酸结构单元的迭代交叉偶联，实现（+）-番红花素C的简短且模块化的全合成。
