通过不对称偕二硼烷的化学选择性氧化获得 MIDA 酰基硼酸盐的模块化和简洁方法:解锁对新型酰基硼的访问†
摘要:
酰基硼酸盐是一类非常有趣且稀有的有机硼酸盐。在温和条件下从容易获得的底物合成这些化合物并获得新型酰基硼一直具有挑战性。我们报告了一种使用不对称偕二硼烷作为关键中间体从末端炔烃/烯烃或乙烯基硼酸酯制备各种 MIDA 酰基硼酸酯的新颖而简洁的途径。该策略的高模块化和温和条件允许轻松获得具有脂肪族、芳香族以及更稀有的杂芳香族、炔基和 α,β-不饱和支架的酰基硼酸盐。据我们所知,这是首个关于双硼化学选择性氧化以及合成 α,β-不饱和酰基硼酸盐的报道。
A general and atom‐economical synthesis of 1,1‐diborylalkanes fromalkenes and a borane without the need for an additional H2 acceptor is reported for the first time. The key to our success is the use of an earth‐abundant zirconium‐based catalyst, which allows a balance of self‐contradictory reactivities (dehydrogenative boration and hydroboration) to be achieved. Our method avoids using an excess
place at α-, β-, and γ-C–H bonds, giving polyborylated products including di-, tri-, tetra-, and even pentaborylalkanes. α-C–H borylation was generally found to be the preferred reaction of primary alkylboronic acid derivatives, whereas β- or γ-borylation also occurred if β- or γ-C–H bonds were located on the methyl group.
Electrooxidative Activation of B−B Bond in B
<sub>2</sub>
cat
<sub>2</sub>
: Access to
<i>gem</i>
‐Diborylalkanes via Paired Electrolysis
作者:Bingbing Wang、Xiangyu Zhang、Yangmin Cao、Long Zou、Xiaotian Qi、Qingquan Lu
DOI:10.1002/anie.202218179
日期:2023.3.27
electrooxidation of a solvent (e.g., DMF)-ligated B2cat2 complex, whereby a solvent-stabilized boryl radical is formed via quasi-homolytic cleavage of the B−Bbond in a DMF-ligated B2cat2 radical cation. Furthermore, a strategy for the electrochemical gem-diborylation of gem-bromides viapairedelectrolysis is developed for the first time, affording a range of versatile gem-diborylalkanes.
该报告描述了溶剂(例如 DMF)连接的 B 2 cat 2络合物前所未有的电氧化,由此通过 DMF 连接的 B 2 cat中B−B 键的准均裂裂解形成溶剂稳定的硼基自由基2自由基阳离子。此外,首次开发了一种通过配对电解对宝石-溴化物进行电化学宝石-二硼基化的策略,提供了一系列通用的宝石-二硼基烷烃。
Anion-Mediated, Stereospecific Synthesis of Secondary and Tertiary Cyclopropylboronates from Chiral Epoxides and <i>gem</i>-Diborylalkanes
作者:Gwanggyun Kim、Minjae Kim、Changsu Ryu、Juhyeok Choi、Seung Hwan Cho
DOI:10.1021/acs.orglett.3c01395
日期:2023.6.9
secondary and tertiary cyclopropylboronates using γ-phosphate-containing gem-diborylalkanes derived from chiral epoxides and gem-diborylalkanes. Our method enables the synthesis of a broad range of enantioenriched secondary and tertiary cyclopropylboronates in good yields with excellent stereospecificity. We demonstrate the versatility of our approach by performing a gram-scale reaction. We also show that