A New, Simple, and General Synthesis of N-Oxides of Iodopyridines and Iodoquinolines via the Diazotization–Iodination of Heterocyclic Amino N-Oxides in the Presence of p-Toluenesulfonic Acid in Water
Abstract The diazotization of a series of N-oxides of aminopyridines and aminoquinolines under the action of sodium nitrite in the presence of KI and p-TsOH in water at room temperature leads to the formation of the corresponding N-oxides of iodopyridines and iodoquinolines in high yields. The method has a general character and can be used for the preparation of 3-, 2-, and 4- N-oxides of iodopyridines
Iodo- or 2-bromopyridine N-oxides were readily magnesiated with i-PrMgCl·LiCl via the iodine or bromine−magnesium exchange. The bromine adjacent to pyridineN-oxide (at the 2- or 6-position) can be regioselectively magnesiated in the presence of other position substituted halogens. This method was tested in various substituted pyridineN-oxide systems, and has been successfully applied to the total