Broadening the Scope of the Gold-Catalyzed [2+2] Cycloaddition Reaction: Synthesis of Vinylcyclobutenes and Further Transformations
作者:M. Elena de Orbe、Antonio M. Echavarren
DOI:10.1002/ejoc.201800170
日期:2018.6.15
The synthesis of 1‐vinyl‐, 3‐vinyl‐ and 3‐alkynylcyclobutenes has been achieved by a gold(I)‐catalyzed [2+2] cycloadditionreaction. One‐pot transformations of the versatile cyclobutenes render cyclopentenes, 2,3‐dihydrofurans, polycyclic skeletons and beyond.
Efficient palladium-catalyzed vinylic C–H alkenylation and allenylation of gem-disubstituted ethylenes with N-tosylhydrazones of arylalkyl and diaryl ketones were achieved to access trisubstituted 1,3-dienes and tetrasubstituted allenes, respectively. An aryl to vinyl 1,4-palladium migration/carbene insertion/β-hydride elimination sequence proceeded to switch the chemo- and regioselectivities to give
The chemodivergent ring-opening of cyclobutanols is described under the carbocatalytic assistance of grapheneoxide (GO). The protocol enables the synthesis of diversely functionalized dienes or indenes (26 examples) based on the amount of GO employed. Spectroscopic (XPS and ssNMR) as well as experimental investigations revealed a direct involvement of the π-domains of GO in tuning the stability of
regiodivergent and stereoselective ring-opening isomerization of vinylcyclopropane was developed with cobalt catalysis. Employing the commercially available Xantphos ligand, the reactions afforded exclusively linear-type 1,3-dienes as the products. Interestingly, when switching the ligand to an amido-diphosphine ligand (PNP), branched-type 1,3-dienes were obtained with high regioselectivity and stereoselectivity