Pfitzner–Moffatt oxidation

The Pfitzner–Moffatt oxidation, sometimes referred to as simply the Moffatt oxidation, is a chemical reaction for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. The oxidant is a combination of dimethyl sulfoxide (DMSO) and dicyclohexylcarbodiimide (DCC). The reaction was first reported by J. Moffatt and his student K. Pfitzner in 1963.[1][2]

Stoichiometry and mechanism

The reaction requires one equivalent each of the diimide, which is the dehydrating agent, and the sulfoxide, the oxidant:

(CH3)2SO + (CyN)2C + R2CHOH → (CH3)2S + (CyNH)2CO + R2C=O

Typically the sulfoxide and diimide are used in excess.[3] The reaction cogenerates dimethyl sulfide and a urea. Dicyclohexylurea ((CyNH)2CO) can be difficult to remove from the product, which is a nuisance.

In terms of mechanism, the reaction is proposed to involve the intermediacy of an alkoxysulfonium ylide.

This reaction has been largely displaced by the Swern oxidation, which also uses DMSO as an oxidant in the presence of an electrophilic activator. Swern oxidations tend to give higher yields and simpler workup.[4][5]

See also

References

  1. ↑ Pfitzner, K. E.; Moffatt, J. G. (1963). "A New and Selective Oxidation of Alcohols". J. Am. Chem. Soc. 85: 3027. doi:10.1021/ja00902a036.
  2. ↑ J. G. Moffatt, “Sulfoxide-Carbodiimide and Related Oxidations” in Oxidation vol. 2, R. L. Augustine, D. J. Trecker, Eds. (Dekker, New York, 1971) pp 1–64.
  3. ↑ John G. Moffatt (1967). "Cholane-24-al". Org. Synth. 47: 25. doi:10.15227/orgsyn.047.0025.
  4. ↑ Tidwell, T. T. (1990). "Oxidation of Alcohols by Activated Dimethyl Sulfoxide and Related Reactions: An Update". Synthesis: 857–870. doi:10.1055/s-1990-27036.
  5. ↑ Lee, T. V. Compr. Org. Synth. 1991, 7, 291–303. (Review)
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