Organic N-containing compounds, including amines, are essential components of many biologically and pharmaceutically important molecules. One strategy for introducing nitrogen into substrates with multiple reactive bonds is to insert a monovalent N fragment (nitrene or nitrenoid) into a C–H bond or add it directly to a C=C bond. However, it has been challenging to develop well-defined catalysts capable of promoting predictable and chemoselective aminations solely through reagent control. Herein, we report remarkable chemoselective aminations that employ a single metal (Ag) and a single ligand (phenanthroline) to promote either aziridination or C–H insertion by manipulating the coordination geometry of the active catalysts.
Allene aziridination generates useful bicyclic methylene aziridine scaffolds that can be flexibly transformed into a range of stereochemically complex and densely functionalized amine-containing stereotriads. The scope of this chemistry has been limited by the poor chemoselectivity that often results when typical dinuclear Rh(II) catalysts are employed with homoallenic carbamates. Herein, Ag(I) catalysts that significantly improve the scope and yield of bicyclic methylene aziridines that can be prepared via allene aziridination are described.
Tunable, Chemoselective Amination via Silver Catalysis. -A chemoselective amination of homoallylic and homoallenic carbamates solely through control of the catalyst/ligand ratio is reported. A simple Ag-based catalyst combined with phenanthroline as ligand is capable to favor either aziridination or C-H insertion. -(RIGOLI, J. W.; WEATHERLY, C. D.; ALDERSON, J. M.; VO, B. T.; SCHOMAKER*, J. M.; J. Am. Chem. Soc. 135 (2013) 46, 17238-17241, http://dx.doi.org/10.1021/ja406654y ; Dep. Chem., Univ. Wis., Madison, WI 53706, USA; Eng.) -H. Haber 23-042
Chemoselective Allene Aziridination via Ag(I) Catalysis. -It is demonstrated that scope and utility of allene aziridination can be greatly increased by employing readily available and tunable Ag(I)-based catalysts. These complexes can, dependent on the ligand, promote aziridination with superior chemoselectivity over conventional Rh-based catalysts. -(RIGOLI, J. W.; WEATHERLY, C. D.; VO, B. T.; NEALE, S.; MEIS, A. R.; SCHOMAKER*, J. M.; Org. Lett. 15 (2013) 2, 290-293, http://dx.doi.org/10.1021/ol303167n ; Dep. Chem., Univ. Wis., Madison, WI 53706, USA; Eng.) -H. Haber 23-088
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