<i>N-</i>Tosyloxycarbamates as a Source of Metal Nitrenes: Rhodium-Catalyzed C−H Insertion and Aziridination Reactions

The rhodium-catalyzed decomposition of N-tosyloxycarbamates to generate metal nitrenes which undergo intramolecular C−H insertion or aziridination reaction is described. Aliphatic N-tosyloxycarbamates produce oxazolidinones with high yields and stereospecificity through insertion in benzylic, tertiary, and secondary C−H bonds. Intramolecular aziridination occurs with allylic N-tosyloxycarbamates to produce aziridines as single diastereomers. The reaction proceeds at room temperature using a rhodium catalyst and an excess of potassium carbonate and does not require the use of strong oxidant, such as hypervalent iodine reagents. A rhodium nitrene species is presumably involved, as both reactions are stereospecific.本文报道了铑催化N-对甲苯磺酰氧基氨基甲酸酯(N-tosyloxycarbamates)分解生成金属氮宾(metal nitrenes)，该金属氮宾可发生分子内C-H插入或氮丙啶化反应。脂肪族N-对甲苯磺酰氧基氨基甲酸酯可在苄基、叔碳及仲碳的C-H键位点发生插入反应，以优异收率与立体专一性得到恶唑烷酮(oxazolidinones)。烯丙基型N-对甲苯磺酰氧基氨基甲酸酯则发生分子内氮丙啶化反应，生成单一非对映异构体形式的氮丙啶(aziridines)。该反应可在室温条件下进行，以铑为催化剂，使用过量碳酸钾，无需使用高价碘试剂(hypervalent iodine reagents)等强氧化剂。鉴于两类反应均具有立体专一性，推测反应过程中涉及铑氮宾(rhodium nitrene)物种。