Synthesis of 4-(alkoxyamino)chroman-2-ones via 6-exo-trig cyclization of carbon-centered radicals into oxime ethers
作者:Carlos A. Bejarano、John E. Díaz、Alix E. Loaiza
DOI:10.1007/s10593-016-1857-z
日期:2016.3
synthesized via a 6-exo-trig cyclization of alkyl radicals obtained from α-bromoesters containing an oxime ether group. In the case of secondary bromides, the best results were achieved using tris(trimethylsilyl)silane as the chain transfer agent and Et3B as the initiator in dichloromethane at room temperature; the corresponding chromanones were produced in 58–70% yield. Low yields of the cyclized compounds
Screening of ligands for the Ullmann synthesis of electron-rich diaryl ethers
作者:Nicola Otto、Till Opatz
DOI:10.3762/bjoc.8.122
日期:——
In the search for new ligands for the Ullmanndiaryl ether synthesis, permitting the coupling of electron-rich aryl bromides at relatively low temperatures, 56 structurally diverse multidentate ligands were screened in a model system that uses copper iodide in acetonitrile with potassium phosphate as the base. The ligands differed largely in their performance, but no privileged structural class could
Hydroxyl‐substituted benzaldimines underwent a RhIII‐catalyzed C−Hactivation and annulation with alkynes to provide novel mesoionicisoquinoline derivatives in moderate to excellent yields using oxygen as an internal anion source. This simple and efficient approach has a broad substrate scope.
Heterodienophilic intramolecular diels-alder reactions of 1,2,4 triazines.
作者:Edward C. Taylor、Joseph L. Pont、John C. Warner
DOI:10.1016/s0040-4020(01)87691-2
日期:1987.1
7-(2'-cyanophenoxy)-6-azalumazines undergo intramolecularDiels-Alderreactions to yield novel polycyclic pyrazines and lumazines. However, the analogous 5-(2'-cyanophenoxy)-1,2,4-triazines fail to undergo cycloaddition, preventing access to the unknown benzfuro[2,3-]-1,2,4-triazine system. Substitution of oxime ethers for nitriles on the dienophilic sidechains of the respective Diels-Alder precursors failed to increase