the reaction of cyanogen bromide with tertiary amines, was applied to a series of functionalized N-alkyl azetidines. This reaction mainly leads to the cleavage of the strained four-membered ring, producing 3-bromo N-alkyl cyanamides in good yield and variable regioselectivity, which can be used as original buildingblocks for the synthesis of nitrogenheterocycles.
von Braun 反应,即溴化氰与叔胺的反应,应用于一系列功能化的 N-烷基氮杂环丁烷。该反应主要导致拉紧的四元环断裂,以良好的产率和可变的区域选择性产生 3-溴 N-烷基氰胺,可用作合成氮杂环的原始构件。
Mechanistic insights into the rearrangement of azetidine N-oxides to isoxazolidines
Meisenheimer rearrangement. This ring expansion leading to isoxazolidines occurs readily, without trapping of the transient N-oxide. Starting with azetidines bearing a nitrile or an ester group at C-2, the rearrangement is regioselective. However, a varying amount of epimerization on the migrating radical is observed, which can also be observed with the related [1,2] Stevens rearrangement.