Use of Strain-Release for the Diastereoselective Construction of Quaternary Carbon Centers
作者:Tobias Pinkert、Mowpriya Das、Malte L. Schrader、Frank Glorius
DOI:10.1021/jacs.1c03492
日期:2021.5.26
formation of quaternary carbon centers with excellent diastereoselectivity via a strain-release protocol. An organometallic species is generated by Cp*Rh(III)-catalyzed C–H activation, which is then coupled with strained bicyclobutanes (BCBs) and a prochiral carbon electrophile in a three-component reaction. This work illustrates a rare example of BCBs in transition metal catalysis and demonstrates their
Structurally Diverse Acyl Bicyclobutanes: Valuable Strained Electrophiles
作者:Brett D. Schwartz、Meng Yao Zhang、Riley H. Attard、Michael G. Gardiner、Lara R. Malins
DOI:10.1002/chem.201905539
日期:2020.3.2
This work reports two efficient pathways for the rapid preparation of over 20 structurally diverse BCB ketones, encompassing simple alkyl and aryl derivatives, as well as unprecedented amino acid, dipeptide, bioisostere, and bifunctional linchpin reagents currently inaccessible using literature methods. Analogues are readily forged in two steps and in high yields from simple carboxylic acids or through
α‐Selective Ring‐Opening Reactions of Bicyclo[1.1.0]butyl Boronic Ester with Nucleophiles
作者:Lin Guo、Adam Noble、Varinder K. Aggarwal
DOI:10.1002/anie.202011739
日期:2021.1.4
The reaction of bicyclo[1.1.0]butyl pinacol boronic ester (BCB‐Bpin) with nucleophiles has been studied. Unlike BCBs bearing electron‐withdrawing groups, which react with nucleophiles at the β‐position, BCB‐Bpin reacts with a diverse set of heteroatom (O, S, N)‐centred nucleophiles exclusively at the α‐position. Aliphatic alcohols, phenols, carboxylic acids, thiols and sulfonamides were found to be
Radical Addition to Strained σ-Bonds Enables the Stereocontrolled Synthesis of Cyclobutyl Boronic Esters
作者:Mattia Silvi、Varinder K. Aggarwal
DOI:10.1021/jacs.9b03653
日期:2019.6.19
steroid boronic ester derivatives can be accessed. Additionally, although the use of electron-rich alkyliodides as radical precursors was found to be ineffective, an alternative route involving alkylsulfonylation of the BCB-boronate followed by reductive desulfonylation provided access to simplealkyl substituted cyclobutane products.
Difunctionalization of C–C σ-Bonds Enabled by the Reaction of Bicyclo[1.1.0]butyl Boronate Complexes with Electrophiles: Reaction Development, Scope, and Stereochemical Origins
作者:Steven H. Bennett、Alexander Fawcett、Elliott H. Denton、Tobias Biberger、Valerio Fasano、Nils Winter、Varinder K. Aggarwal
DOI:10.1021/jacs.0c07357
日期:2020.9.30
being used in difunctionalization reactions. We demonstrate that highly strained bicyclo[1.1.0]butyl boronate complexes (strain energy: ca. 65 kcal/mol), which were prepared by reacting boronic esters with bicyclo[1.1.0]butyl lithium, react with electrophiles to achieve the diastereoselective difunctionalization of the strained central CC -bond of the bicyclo[1.1.0]butyl unit. The reaction shows
CC σ 键的双官能化反应有可能简化对难以制备的分子的访问。然而,这种反应的发展具有挑战性,因为 CC σ 键通常是不活泼的。利用多环碳环的高环应变能是削弱和促进 CC σ 键反应的常用策略,但在双官能化反应中使用高应变 CC σ 键的例子有限。我们证明了通过硼酸酯与双环 [1.1.0] 丁基锂反应制备的高度应变的双环 [1.1.0] 丁基硼酸酯配合物(应变能:约 65 kcal/mol)与亲电子试剂反应以实现非对映选择性双环[1.1.0]丁基单元的应变中心C-C-键的双官能化。该反应显示出广泛的底物范围,一系列不同的亲电子试剂和硼酸酯被成功地用于形成具有高非对映选择性的多种 1,1,3-三取代环丁烷(>50 个实例)。基于实验数据和 DFT 计算的组合,观察到的高非对映选择性已被合理化,这表明单独的协调和逐步反应机制正在运行,具体取决于所使用的迁移取代基和亲电子试剂。