Homoallylboration and Homocrotylboration of Aldehydes
摘要:
A simple method for addition of homoallylic fragments to aldehydes is described. Cydopropanated allylboration reagents react with aldehydes in the presence of PhBCl2 to give high yields of bishomoallyl alcohols. Cyclopropanated cis- and trans-crotyl reagents afford the corresponding 1,3-anti- and 1,3-syn-methyl-substituted "homocrotylated" alcohols with high selectivity, consistent with a Zimmerman-Traxler transition state. Accordingly, the optically active alpha-substituted reactant affords the E-substituted product in 97:3 er.
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。
The first 1,3-boronate rearrangement to ketones is reported. The reaction is driven by visible light irradiation, leading to various β-keto tertiary alcohols under metal-free conditions. The excited state overcomes the energy barrier for the rearrangement, and mechanistic studies have excluded a free-radical reaction pathway.
[EN] SMALL MOLECULE INHIBITORS OF LACTATE DEHYDROGENASE AND METHODS OF USE THEREOF<br/>[FR] INHIBITEURS À PETITE MOLÉCULE DE LACTATE DÉSHYDROGÉNASE ET PROCÉDÉS POUR LES UTILISER
申请人:US HEALTH
公开号:WO2016109559A3
公开(公告)日:2016-08-25
Intermolecular Radical Addition to Ketoacids Enabled by Boron Activation
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。
Homoallylboration and Homocrotylboration of Aldehydes
作者:Wenbo Pei、Isaac J. Krauss
DOI:10.1021/ja2048682
日期:2011.11.23
A simple method for addition of homoallylic fragments to aldehydes is described. Cydopropanated allylboration reagents react with aldehydes in the presence of PhBCl2 to give high yields of bishomoallyl alcohols. Cyclopropanated cis- and trans-crotyl reagents afford the corresponding 1,3-anti- and 1,3-syn-methyl-substituted "homocrotylated" alcohols with high selectivity, consistent with a Zimmerman-Traxler transition state. Accordingly, the optically active alpha-substituted reactant affords the E-substituted product in 97:3 er.