Enantioselective Synthesis of Oxazaborolidines by Palladium‐Catalyzed N-H/B-H Double Activation of 1,2‐Azaborines
Enantioselective Synthesis of Oxazaborolidines by Palladium‐Catalyzed N-H/B-H Double Activation of 1,2‐Azaborines
复制标题
钯催化 N-H/B-H 1,2-氮杂硼烷双活化对映选择性合成恶唑硼烷
DOI：
10.1002/anie.202113558
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Nakamura Hiroyuki
中科院分区：
文献类型：
--
作者：
Morita Taiki;Murakami Hiroki;Asawa Yasunobu;Nakamura Hiroyuki
钯催化的1，2-二氢-1，2-苯并氮杂硼杂环的N-H/B-H双活化通过与乙烯基碳酸亚乙酯的环加成进行，以31- 96%的产率产生多环恶唑硼烷。该过程的关键步骤是从硼酸盐中间体释放分子氢。使用SPINOL衍生的亚磷酰胺作为手性配体，以良好至高产率合成手性恶唑硼烷，具有优异的对映选择性（高达95%ee）。得到的恶唑硼烷的乙烯基基团经历复分解，Heck反应，和Wacker氧化，而不影响恶唑硼烷框架。
A palladium‐catalyzed N−H/B−H double activation of 1,2‐dihydro‐1,2‐benzazaborines proceeded via cycloaddition with vinyl ethylene carbonate to produce polycyclic oxazaborolidines in 31–96 % yield. The key step in this process is the release of molecular hydrogen from a borate intermediate. Using a SPINOL‐derived phosphoramidite as a chiral ligand, chiral oxazaborolidines were synthesized in good to high yields with excellent enantioselectivity (up to 95 % ee). The vinyl group of the resulting oxazaborolidine underwent metathesis, Heck reaction, and Wacker oxidation without affecting the oxazaborolidine framework.