Alcohol Oxidation Catalysts with Higher Activity than TEMPO——AZADOL®

Recently, environmentally friendly oxidation reactions catalyzed by a nitrogen-oxygen radical, TEMPO, have attracted attention. Iwabuchi et al. reported that a nitrogen-oxygen radical, 2-azadamantane-N-oxygen (AZADO), efficiently catalyzed oxidation reaction of alcohols.1-3 Compared with TEMPO, AZADO presents higher oxidizability, which makes it possible to oxidize even sec-alcohols with large site resistance in high yields. In contrast, 2-hydroxy-2-azaadamantane (AZADOL®), developed by Iwabuchi et al. has better storage stability than AZADO. In the presence of an oxidizing agent, this catalytic reaction undergoes the mechanism of AZADO, so that AZADOL® presents the same properties as AZADOL. In addition, the oxidation reaction of nitrogen carbonyl salts derived from AZADOL® has been investigated.

Advantage of AZADOL®

• High catalytic activity (better than TEMPO)

• Prone to oxidize secondary alcohols with high site resistance

• Depending on the co-oxidant, a wide range of oxidation reactions can be applied (Co-oxidant: NaOCl, NaClO2, PhI(OAc)2, O2, DIAD）4

Oxidation of Alcohols under Anelli’s Condition 1-2

Aerobic Oxidation of Alcohols 5

Oxidation of Alcohols to Carbonyl Compounds with Mitsunobu Reagent 6

Functional-group-selective oxidation proceeds by use of Mitsunobu reagent DIAD as a co-oxidant.

One-Pot Oxidative Cleavage of 1,2-Diols to (Di) Carboxylic Acids 7

Oxidative cleavage of 1,2-diols to carboxylic acids proceeds by use of hypervalent iodine compound PhI(OAc)2 as a co-oxidant.

References

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2. Y. Iwabuchi, M. Shibuya, M. Tomizawa, Y. Osada, PCT Int. Appl. WO 2009145323, 2009.

3. M. Hayashi, M. Shibuya, Y. Iwabuchi, Org. Lett. 2012, 14, 154. https://doi.org/10.1021/ol2029417

4. Y. Iwabuchi, Chem. Pharm. Bull. 2013, 61, 1197. https://doi.org/10.1248/cpb.c13-00456

5. M. Hayashi, Y. Sasano, M. Shibuya, Y. Iwabuchi, Chem. Pharm. Bull. 2011, 59, 1570. https://doi.org/10.1248/cpb.59.1570

6. M. Hayashi, M. Shibuya, Y. Iwabuchi, J. Org. Chem. 2012, 77, 3005. https://doi.org/10.1021/jo300088b

7. M. Shibuya, T. Shibuta, Y. Iwabuchi, Org. Lett. 2012, 14, 5010. https://doi.org/10.1021/ol3021435