Copper-Mediated Selective Cross-Coupling of 1,1-Dibromo-1-alkenes and Heteronucleophiles: Development of General Routes to Heterosubstituted Alkynes and Alkenes
site-selective, double, or alkynylative cross-coupling, therefore providing divergent and straightforward entries to numerous building blocks such as bromoenamides, ynamides, ketene N,N-acetals, bromoenol ethers, ynol ethers, keteneO,O-acetals, or vinylphosphonates and further expanding the copper catalysis toolbox with useful and versatile processes.
Hetero-Tetradehydro-Diels–Alder Cycloaddition of Enynamides and Cyanamides: Gold-Catalyzed Generation of Diversely Substituted 2,6-Diaminopyridines
作者:Nikolay V. Shcherbakov、Dmitry V. Dar’in、Vadim Yu. Kukushkin、Alexey Yu. Dubovtsev
DOI:10.1021/acs.joc.1c00558
日期:2021.5.21
hetero-tetradehydro-Diels–Alder cycloaddition of enynamides and cyanamides comprises an efficient route to diversely substituted 2,6-diaminopyridines (28 examples; yields up to 99%). The reaction proceeds under very mild conditions (DCM, rt) with high functional group tolerance. The obtained 2,6-diaminopyridines represent a useful synthetic platform with an easily modulated substitution pattern for subsequent
entry to the corresponding β-silylenamides and -acrylates, which were formed with high levels of regio- and stereoselectivities. A highly efficient catalytic silylcupration of activated alkynes is reported. Upon reaction with silylboronates and methanol in THF at room temperature in the presence of copper(I) fluoride tris(triphenylphosphine), a range of ynamides and propiolates were found to undergo a
α-Fluoroenamides, potent rigid fluorinated bioisosters of ureas, have been synthesized by a highly regio- and stereo-selective hydrofluorination of ynamides in anhydrous HF. This reaction provides the first general entry to α-fluoroenamides and can easily be applied to a wide range of substrates.
A highly regio- and stereoselective trans-iodofluorination reaction of ynamides with NIS and Et3N·3HF has been achieved, affording (E)-α-fluoro-β-iodoenamides in moderate to good yields. The reaction proceeds under mild reaction conditions and exhibits good functional group compatibility.