copper‐catalyzed cross‐coupling of 1,2‐dihaloalkenes and amides leads to cyclic β‐haloenamides, which can participate in a second cross‐coupling reaction to efficiently synthesize highly functionalized cyclic enamides. The selectivity of the intramolecular coupling between exo‐ and endocyclic regioisomers is a crucial synthetic factor and can be influenced by the structure of the substrate and the reaction conditions
Comparison between Conventional and Nonconventional Methods for the Synthesis of Some 2-Oxazolidinone Derivatives and Preliminary Investigation of Their Inhibitory Activity Against Certain Protein Kinases
作者:S. Ziane、M. M. Mazari、A. M. Safer、A. Sad El Hachemi Amar、S. Ruchaud、B. Baratte、S. Bach
DOI:10.1134/s1070428019070248
日期:2019.7
A series of propargyl and allyl carbamates were prepared directly from propargyl and allyl alcohols and phenyl or cyclohexyl isocyanate or indirectly by generating the isocyanates in situ from the corresponding Cbz-protected amines. The obtained carbamates underwent intramolecular nucleophilic cyclization in presence of cesium hydroxide monohydrate as a base catalyst under conventional and ultrasonic
On treatment with catalytic amounts of gold(I) chloride (AuCl) and a base co-catalyst, O-propargyl carbamates smoothly undergo a 5-exo-dig cyclization at room temperature to afford 4-methylene-2-oxazolidinones in high yield. Substrates with a substituent at the alkyne terminus stereoselectively give rise to (Z)-4-alkylidene-2-oxazolidinones.
Direct C–H/N–H dehydrogenative coupling is a promising yet thermodynamically unfavorable transformation in the absence of a sacrificial hydrogen acceptor. Herein, a conceptually novel oxidant-free dehydrogenative amination of alkenes through a synergistic photoredox and cobaltcatalysis with H2 evolution has been achieved. With this approach, a wide range of five-membered N-heterocycles were synthesized