Ionic liquids as media for nucleophilic ring opening fluorination of aziridines

Abstract

We have developed an efficient methodology for nucleophilic ring opening fluorination of aziridines by KF-2H2Ü or KHF2 in an ionic liquid without any external sources, which resulted in a convenient route to ß-fluoro amines. The ionic liquid acts not only as a solvent but also as a phase transfer catalyst in the reaction.

Synthesis of Fluorine‐Containing Molecular Entities Through Fluoride Ring Opening of Oxiranes and Aziridines

“…Although using alkali and tetraalkylammonium hydrofluorides for the ring opening of aziridines is not completely unknown, (see, for example, the work of Kroutil et al), no recent reference was found with respect to the utilization of tetraalkylammonium hydrofluorides for the ring opening of aziridines and only a single example was found, where KHF 2 was used. Shibata and co‐workers reported successful ring opening of bicyclic N ‐sulfonylaziridines with different potassium fluorides (KF, KF/2H 2 O or KHF 2 ) in ionic liquid [bmim][BF 4 ], which served as both solvent and phase‐transfer catalyst (Table ).…”

“…KF/2H 2 O was effective enough to transform reactive oxiranes into fluorinated amines, but less reactive oxiranes performed better when KHF 2 was used. N ‐Nosylaziridines gave better yields than their N ‐tosyl analogues …”

Einführung von Fluor und fluorhaltigen funktionellen Gruppen

“…[13a, 103a, 126] Dagegen ist die nucleophile Fluorierung an sekundären oder tertiären sp 3 -Kohlenstoffzentren von Natur aus schwieriger, und eine allgemeine, mit funktionellen Gruppen vereinbare Methode steht derzeit nicht zur Verfügung. [128] Epoxide [129] und Aziridine [130] werden durch Fluorid nucleophil zu vicinalen Fluoralkoholen bzw. Die Halogenfluorierung von Alkenen gelang durch Umsetzung des Alkens mit N-Iodsuccinimid und Tetraalkylammoniumhydrogenfluorid.…”

Efficient Regioselective Ring Opening of Activated Aziridine‐2‐Carboxylates with [18F]Fluoride

“…, Ring opening was recently carried out with the use of KF⋅2 H 2 O/Bu 4 NHSO 4 , KF⋅2 H 2 O, or KHF 2 in an ionic liquid and triethylamine trihydrofluoride . , However, these methods are not convenient when using the radionuclide fluorine‐18 ( t 1/2 =109.7 min) . Fluorine‐18 is one of the most frequently used radionuclides for positron emission tomography (PET), which is an important technique for imaging and studying biochemical processes in vivo.…”