Practical PreparationMethods for Highly Active Azaadamantane-Nitroxyl-Radical-Type OxidationCatalysts

We have recently disclosed that a less hindered class of nitroxylradicals, i.e., 2-azaadamantan- N-oxyl(AZADO), 1-Me-AZADO, and 9-azabicyclo[3.3.1]nonan- N-oxyl (ABNO), exhibit marked catalyticactivity for the oxidation of alcohols with the aid of environmentallyfriendly oxidants, offering a green and sustainable option for currentalcohol oxidation. Encouraged by their outstanding catalytic performance,we envisioned the development of scalable routes to these radicalsthat could be extended to the commercialization of these radicalsfor benchtop use as well as for industrial use as optional reagentsthat complement TEMPO, the flagship compound of stable nitroxylradicals. We herein describe short and reproducible preparationmethods for AZADO and 1-Me-AZADO, featuring an efficient constructionof the 2-azaadamantane skeleton. 1 Introduction 2 1-Me-AZADO and AZADO: First-Generation Syntheses 3 Second-Generation Synthesis of 1-Me-AZADO 4 Synthetic Venture towards 2-Azaadamantane: Second-GenerationSynthesis of AZADO 5 Conclusion