Reactions of HDDA-Derived Benzynes with Sulfides: Mechanism, Modes, and Three-Component Reactions
作者:Junhua Chen、Vignesh Palani、Thomas R. Hoye
DOI:10.1021/jacs.6b01025
日期:2016.4.6
We report here reactions of alkyl sulfides with benzynes thermally generated by the hexadehydro-Diels-Alder (HDDA) cycloisomerization. The initially produced 1,3-betaine (o-sulfonium/aryl carbanion) undergoes intramolecular proton transfer to generate a more stable S-aryl sulfur ylide. This can react in various manners, including engaging weak acids (HA) in the reaction medium. This can produce transient
BF<sub>3</sub>-Promoted, Carbene-like, C–H Insertion Reactions of Benzynes
作者:Hang Shen、Xiao Xiao、Moriana K. Haj、Patrick H. Willoughby、Thomas R. Hoye
DOI:10.1021/jacs.8b10206
日期:2018.11.21
Boron trifluoride is observed to promote a variety of C-H insertion reactions of benzynes bearing pendant alkyl groups. Computations and various mechanistic studies indicate that BF3 engages the strained π-bond to confer carbene-like character on the adjacent, noncoordinated benzyne carbon. This represents an unprecedented catalytic role for a non-transition metal such as BF3.
Multiheterocyclic Motifs via Three-Component Reactions of Benzynes, Cyclic Amines, and Protic Nucleophiles
作者:Sean P. Ross、Thomas R. Hoye
DOI:10.1021/acs.orglett.7b03458
日期:2018.1.5
general, three-component reaction strategy for the construction of compounds containing multiple heterocycles is described. Thermal benzyne formation (by the hexadehydro-Diels–Alder (HDDA) reaction) in the presence of tertiary cyclic amines and a protic nucleophile (HNu) gives, via ring-opening of intermediate ammonium ion/Nu– ion pairs, heterocyclic products. Many reactions are efficient even when
Ruthenium-Catalyzed C−C Bond Cleavage of 2<i>H</i>
-Azirines: A Formal [3+2+2] Cycloaddition to Fused Azepine Skeletons
作者:Tengfei Li、Fen Xu、Xincheng Li、Chunxiang Wang、Boshun Wan
DOI:10.1002/anie.201510820
日期:2016.2.18
2H‐azirines can serve as three‐atom synthons by C−C bond cleavage, however, it involves a high energy barrier under thermal conditions (>50.0 kcal mol−1). Reported is a ruthenium‐catalyzed [3+2+2] cycloaddition reaction of 2H‐azirines with diynes, thus leading to the formation of fused azepine skeletons. This approach features an unprecedented metal‐catalyzed C−C bond cleavage of 2H‐azirines at room
The high efficiency and fidelity of click chemistry permits a large number of diverse dendrimers encompassing a wide variety of functionalities at the chain ends, repeat units, and/or core to be prepared. Almost quantitative yields were obtained during the synthesis. In some cases, filtration or solvent extraction was the only method required for purification. These features represent a significant advancement in dendrimer chemistry and demonstrate an evolving synergy between organic chemistry and functional materials.