A new radical cyclization method for the formation of C(sp3)–C(sp3) and C–O bonds via MnO2-promoted alkene carboesterification with anhydrides is developed.
An asymmetrichydrogenation of aroylacrylic acidscatalyzed by RuPHOX-Ru catalyst has been developed, affording the corresponding chiral γ-lactones in high yields and with up to 93% ee. The methodology has the advantage of utilizing easily accessible substrates and has therefore expand the scope of the resulting chiral γ-lactones. Furthermore, high catalytic efficiency was achieved in that the reduction
A photocatalyzed oxidation of functionalized cyclobutanones to access γ-lactones has been performed in acetonitrile at room temperature, using 9,10-anthraquinone as catalysts in the presence of TFA. The process furnish good to excellent yields of the desired compounds in 4–16 h reaction and after simple filtration of the recyclable catalyst.
Quick Installation of a 1,4-Difunctionality via Regioselective Nickel-Catalyzed Reductive Coupling of Ynoates and Aldehydes
作者:Sanjeewa K. Rodrigo、Hairong Guan
DOI:10.1021/jo301790q
日期:2012.9.21
The development of efficient methods for the synthesis of molecules with 1,4-difunctionalities has been a dire need of the synthetic community. In this work, intermolecular reductive coupling of ynoates and aldehydes (in the presence of a silane) has been accomplished for the first time using catalytic amounts of Ni(COD)(2), an N-heterocyclic carbene ligand, and PPh3. High regioselectivity has been demonstrated for the multicomponent coupling reactions, and more than a dozen invaluable silyl-protected gamma-hydrox-alpha,beta-enoates have been synthesized. This methodology provides a quick entry to many other 1,4-difunctional compounds and oxygen-containing five-membered rings. The intermediacy of metallacycles in the catalytic process has been established by deuterium-labeling experiments.
Aniline‐Type Hypervalent Iodine(III) for Intramolecular Cyclization via C−H Bond Abstraction of Hydrocarbons Containing N‐ and O‐Nucleophiles
作者:Yuna Nishiguchi、Katsuhiko Moriyama
DOI:10.1002/adsc.202100316
日期:2021.7
We developed a method for the preparation of (diacetoxyiodo)-2-(N-alkylamido)benzene as an aniline-type hypervalent iodine(III). We also achieved direct cyclizations via C−H bond abstraction, such as the Hofmann-Löffler-Freytag reaction, a direct amination, and a direct lactonization, using the aniline-type hypervalent iodine(III) to obtain corresponding products in high yields.