Manganese-Catalyzed Borylation of Unactivated Alkyl Chlorides
作者:Thomas C. Atack、Silas P. Cook
DOI:10.1021/jacs.6b03157
日期:2016.5.18
of (bis)pinacolatodiboron with a wide range of alkyl halides, demonstrating the first manganese-catalyzed coupling with alkyl electrophiles. This method allows access to primary, secondary, and tertiary boronic esters from the parent chlorides, which were previously inaccessible as coupling partners. The reaction proceeds in high yield with as little as 1000 ppm catalyst loading, while 5 mol % can
A copper(II)-catalyzed borylation of alkyl halides with bis(pinacolato)diboron (B2pin2) has been developed, which can be carried out in air, providing a wide range of primary, secondary, and some tertiary alkylboronates in high yields. A variety of functional groups are tolerated and the protocol is also applicable to unactivated alkyl chlorides (including 1,1- and 1,2-dichlorides). Preliminary mechanistic
Employing anilines as nucleophiles in double carbonylation is a longstanding challenge. In this communication, a Mn(III)-promoted double carbonylation of alkylborates or Hantzsch esters with anilines toward the synthesis of α-ketoamides has been developed. By using easily available potassium alkyltrifluoroborates or Hantzsch esters as the starting material, and cheap and non-toxic Mn(OAc)3 ⋅ 2H2O as
α-ketoacids enabled by the Lewis acid activation. The in situ boron complex formation is confirmed by various spectroscopic measurements and mechanistic probing experiments, which facilitates various alkyl boronic acid addition to the carbonyl group and prevents the cleavage of the newly-formed C-C bond. Diversely substituted lactates can be synthesized from readily available alkyl boronic acids and ketoacids
由于所得烷氧基自由基容易断裂,分子间自由基加成到羰基上是困难的。迄今为止,酮的分子间自由基加成是构建季碳中心的一种有价值的方法,仍然是一项艰巨的合成挑战。在这里,我们报告了第一个可见光诱导的分子间烷基硼酸加成到 α-酮酸通过路易斯酸活化实现的。各种光谱测量和机械探测实验证实了原位硼配合物的形成,这有助于将各种烷基硼酸加成到羰基上,并防止新形成的 CC 键断裂。在室温下,仅在可见光照射下,无需任何额外试剂,即可由易得的烷基硼酸和酮酸合成不同取代的乳酸酯。这种硼活化方法可以扩展到作为自由基前体的烷基二氢吡啶与用于伯、仲和叔烷基自由基加成的外部硼试剂。在流动反应器中的无金属条件下,药学上有用的抗胆碱能前体很容易放大到数克。
Electrochemical Borylation of Alkyl Halides: Fast, Scalable Access to Alkyl Boronic Esters
作者:Bingbing Wang、Pan Peng、Wan Ma、Zhao Liu、Cheng Huang、Yangmin Cao、Ping Hu、Xiaotian Qi、Qingquan Lu
DOI:10.1021/jacs.1c06473
日期:2021.8.25
Herein, a fast, scalable, and transition-metal-free borylation of alkyl halides (X = I, Br, Cl) enabled by electroreduction is reported. This process provides an efficient and practical access to primary, secondary, and tertiary boronic esters at a high current. More than 70 examples, including the late-stage borylation of natural products and drug derivatives, are furnished at room temperature, thereby