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
Density functional theory (DFT) calculations reveal that the two adjacent iodines in o-diiodoarenes play critical roles in the formation of aryne. The nucleophilic attack of hydride to the electrophilic iodine requires that the adjacent iodine act as a directing group to accelerate this process, whereas mono-substituted iodobenzene lacking the neighboring-group participation makes it difficult. The in-situ-formed
在这里,我们记录了以“旧”邻二碘芳烃作为芳炔祖体的芳炔化学的重新发明。我们建立了 NaH 介导的活化策略,以受控方式生成高反应性芳炔物种。所得芳炔可以有效地参与与未活化酮的C-C σ键插入反应,这是现有方法难以实现的。密度泛函理论 (DFT) 计算表明o中的两个相邻碘-二碘芳烃在芳炔的形成中起关键作用。氢化物对亲电子碘的亲核攻击需要邻近的碘充当导向基团来加速这一过程,而缺乏邻近基团参与的单取代碘苯则使其变得困难。酮原位形成的烯醇化物被建议采用四聚体聚集体与芳烃反应,这解释了具有大取代基的底物的高区域化学性。
Drastic fluorine effect: complete reversal of the selectivity in the Au-catalyzed hydroalkoxylation reaction of fluorinated haloalkynes
The gold-catalyzed hydration reaction of haloalkynes is highly regioselective producing 2-halomethylketones as the sole products. Herein, we document a drastic fluorineeffect where the reaction of 1-halo-3,3-difluoroalkynes as substrates leads to a complete reversal of selectivity and produces 3,3-difluoroesters as the unique products.
作者:Andreas Mavroskoufis、Arielle Rieck、Matthew N. Hopkinson
DOI:10.1016/j.tet.2021.132497
日期:2021.11
in N-heterocyclic carbene (NHC) organocatalysis, undergo NorrishtypeII elimination reactions under irradiation with UVA light in analogy to structurally related aromatic ketones. Moreover, efficient Norrish-Yang cyclization was observed from an adamantyl-substituted derivative. These results further demonstrate the ability of NHCs to influence the absorption properties and photochemical reactivity