Synthesis of 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate and 4-acetamido-(2,2,6,6-tetramethyl-piperidin-1-yl)oxyl and their use in oxidative reactions

摘要: We describe the synthesis of lesser-known stoichiometric oxidation reagent 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (1, Bobbitt's salt), as well 4-acetamido-(2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (2, AcNH-TEMPO). Several representative reactions are also presented to demonstrate salt's oxidative capabilities. salt has a range applications, from various alcohols their corresponding carbonyl derivatives cleavage benzyl ethers, whereas 2 been shown serve catalytic or oxidant. The oxyl radical can be obtained in 85% yield over two steps on 1-mole scale commercially available 4-amino-2,2,6,6-tetramethylpiperidine (5), and is far more cost-effective prepare in-house than purchase commercially. An additional step converts into oxoammonium salt) 88% yield, with an overall 75%. takes ∼5 d complete. Oxoammonium salts metal-free, nontoxic environmentally friendly oxidants. Preparation 1 inherently 'green', water used solvent use unfriendly materials minimal. Moreover, after it used, spent oxidant recovered regenerate 1, thereby making process recyclable.