You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via8.1.1 Mechanistic Understanding
Please login to access the full content or check if you have access via
Dornan, L. M.; Hughes, N. L.; Muldoon, M. J., Science of Synthesis: Catalytic Oxidation in Organic Synthesis, (2017) 1, 530.
Nitroxyl radicals can be used in a number of different ways for alcohol oxidation, and the mechanism depends on the nature of any cocatalyst and the terminal oxidant being used. When hypochlorite/bromide, nitrogen dioxide, or hypervalent iodine reagents [e.g., (diacetoxyiodo)benzene] are used, these oxidize the radical (and its reduced form) to the corresponding oxoammonium salt (e.g., 6), as illustrated in Scheme 2 for the case of TEMPO (5). The oxoammonium cation can then carry out a two-electron oxidation of alcohols to carbonyl compounds. The mechanism of this has recently been studied in detail using both experimental results and density functional theory (DFT).[6,7] In Scheme 3, proposed transition states under neutral and basic conditions are illustrated. Under neutral conditions, it is suggested that hydride transfer from the alcohol to the electrophilic oxygen occurs, followed by proton transfer to the nitrogen. These studies found that using pyridine as a base lowered the activation energy and increased the rate of alcohol oxidation, although, as we will see in this chapter, reactions are not always run under basic conditions.
Meeeeeeeeee eeeee eee ee eeee ee eeeeeeeeeeeeee eeeeeeee,[8] eee eeeeeeeeee eeee ee eeeeeee ee eeeee eee ee eeeeeeeee. Meee eeeeee eee (eeeeeeeeeeeee)eeeeeee eee eeeeeeee ee eeeeeeee eeeeeeee, eeeee eeee ee ee eeee ee eeeeee. Meee eeeeeeee eeeeeee ee eeee ee eeeeeee eee eeeeeeeeeee eeee, eeeeeeeee eeeeeee ee eeeeeeee eeeeeee eee ee eeee ee eeeeeeeee eee eeeeeee eee eeeee eeeeeee eeeeeeeeee, ee eeeeeeeee eeeeee eee eeeeeee eeeeeeee eeeeeeee ee eeeeeeee eeeeeee. Meeeeeeeeeeee, ee eeeeee eeeeee ee eeeeeeee eeeeeee eeeeee eeeeeeeee eeeeeeeeee ee ee eeee. Meeeee eeee, eeeeee eeeeeee, eeee-eeeee eeeeeee, eee eeee eeeeeee eee eeeeeeeee eeee ee eeeeeee ee eeeeeeee eeeeeee eeeeeee ee eeeeeeeee eeeeeeee eeeeeee eee.
Meeeee 8 Meeeeeeeee Meeeeeeee Meeee eee Meeeeeeeee eeee ee Meeeeeeeeee Meee
Meeeee 8 Meeeeeee Meeeeeeeee Meeeee eee Meeeeee Meeeeeeee ee ee Meeeeeeeeee Meeeee eeeee Meeeeee eee Meeee Meeeeeeeee[8,8]
Meeeeee eeeeee/eeeeeeee eeeeeeeee eeeeeee eee eeee eeeeeeeee ee eeee eeeeeee, eee eeeee eeeeeee ee eee eeeeeee ee eeeeeeeeeee eeeeeeeeeeee. Mee eeeeeeeee ee eee eeeeee/MMMMM eeeeee eee eeee eeee eeeeeee; ee eeeeeeeeee, Meeee eee ee-eeeeeee eeee eeeeeeeee eeeeeeee eeeeeeeeeee eeeeeeeeeeeeee ee eeeeee eeeee.[8–88] Mee eeeeeeee eeeeeeeee eeeee eee e eeeeee eeee eeeeee(M) eeeeeeeeeeeeeeeeeeeeeeeee, 8,8′-eeeeeeeee, eee 8-eeeeee-8M-eeeeeeeee (MMM) ee eeeee ee Meeeee 8. Me eeee eeeeeee eeeeee/MMMMM eeeeeee, eee eeeee eee eeeeeee eeee ee eeeeee, eeee eeeeeeee eee eee-eeeeeeee eeeeeeeeee. Meeeee(MM) ee eeeeeeeeeee eee eee eeeeeeeee ee eee eeeeeee eee eee eee ee eeeeee(MM) eeeee ee eeeeeeeeee ee eeeeeeee. Me eee eeee ee eee eeeeee(M)/MMM eeeeee, ee ee eeeeeeee eeee eeeeeeeee (eeeeeeeee ee eeee ee eeee 8) eeeeeeeeeeee eee eeeeeee eee eeee MMM ee eeeeee ee e eeeeee. Me eeeeee(MM) eeeee eee eeee eeeeeeeee, eeee eeeeeeeee ee eee eeeeeeee ee eeee eeeeee eee ee ee eeeeeeeee ee eee e eeeeeeee eeee ee eee eeeeeeee. Meeee ee eeeee ee eeeeeee eee eeee ee eeeeeeee; ee ee eeeeeeeee eeeeeeeeee ee eee ee eeeeeee eeee eeee ee 8,8-eeeeeeeeeeee[8.8.8]eeeee-8-eee ee eeee eeeeeee eee eee ee eeee eeeeeeeeeeee. Me eeeeeeeee ee eeeee eee eeeeee(M)/MMM eeeeee eee eeeeeeeeee eeeeeeeee ee eeee ee eeee eee eeeeee ee eeeeee eeeeee ee eeee-eeeeeeeee eeeeeeeeee eeee eeeee eeeeeee eeeeeeeeeeeee.[88]
Meeeee 8 Meeeeeeee ee Meeeeee Meeeeeeee Meeee e Meeeee(M)/MMMMM Meeeee[8]
Meeeeeee eee eeeeeeeeee eeeee ee Meeeee 8, eee eeeeeeee eeeeeeee eeee eee eeeeeeee ee eee eeeeeeee eeeeeee (eeee 8) ee eeeeeee ee eeee eeeee eee e eee-eeeeeeee eeeeeeeeee eeeee eeee eee eeeeeee eeeeeeeeeee ee eeeeee. Me eee eeee ee eeee eeeeee/MMMMM eeeeeee, eeee eeeeeee ee eeeeeeeee eee eeeeeee eeeeeeee eee eeeeeeeee eeeeeeee eee eee eeeeeee eeeeeeee. Meee ee eeeeeee ee ee eee ee eeeeee eeeeeeeee (ee eeeeeeeee eeeeeeee eee eeeeeee); eeeeeeeee eeee MMMMM ee e eeeeeeeeee eeee eeeeeeee eeeeeee eeee ee MMMM (8) ee MMMMM (8) eeeeeee eeeeeeeee eeeeeeee ee ee eeeeeeeeeee eeeeeeee ee eeee eeeeee eeeeeee. Me Meeeee 8, eee eeeeeeeeee eeeeee 8 (eee eee MMMMM eeeeee) eee 8 (eee eee MMMM eeeeee) eee eeeee eeeee eeee eeeee eeeeeeee eee eeeeeeeee eeeeeee eeeeeeeeee (eeeeeeeeee ee MMM).[88] Me eee ee eeee eeee ee eee eeee ee MMMMM eeeee ee e eeeeeeeeeee eeeeeeeeee eeeeeee eeeeeee eee eeeeeeeee eeeeeeee, eee eeeeee eeeeeeeeee ee eeeeee eeee MMMM ee eeeeeeee (eeeeeee eeeeeee eeee eeee eeeeeeee eeee MMMMM). Meeee eeeeeeeeee eeeeeee eee ee eeeeeeeee eeee eeeeeeeeeeee eeeeeeeeeeee, eeeee eee eeeeeeeee eeeee.
Meeeee 8 Meeeeeeeee Meeeee eee Meeeeeeeee Meeeeeee eee Meeeee/MMMMM eee Meeeee/MMMM Meeeeeeee Meeeeee Meeeeeeee[88]
M8 | M8 | Meeeeeeeee Meeee Meeeee (eeee · eee−8) | Mee | |
---|---|---|---|---|
8 | 8 | |||
Me | Me | 88.8 | 8.8 | [88] |
Me | M | 88.8 | 8.8 | [88] |
Me | M | 88.8 | – | [88] |
References
[6] | Meeeeee, M. M.; Meeeeeeee, M. M.; Meeeee, M. M.; Meeeee, M. M.; Meeee, M. M., M. Mee. Meee., (8888) 88, 8888. |
[7] | Meeeee, M. M.; Meeee, M. M.; Meeee, M. M.; Meeee, M. M.; Meeeee, M. M.; Meeeeeeeee, M. M., M. Mee. Meee., (8888) 88, 8888. |
[8] | Meeeeeeeee, M. M.; Meeeeee, M. M., Meeeeeeeeeee Meee, (8888) 88, 88. |
[9] | Meeeee, M. M.; Meeeee, M. M.; Meeee, M. M., M. Me. Meee. Mee., (8888) 888, 8888. |
[10] | Meeeee, M. M.; Meeeee, M. M.; Meeee, M. M., MMM Meeee., (8888) 8, 8888. |
[11] | Meeeee, M. M.; MeMeee, M. M.; Meeeeee, M. M.; Meeee, M. M., M. Me. Meee. Mee., (8888) 888, 88888. |
[12] | Meeeee, M. M.; Meeee, M. M., M. Me. Meee. Mee., (8888) 888, 88888. |