Cope reaction

The Cope reaction or Cope elimination, developed by Arthur C. Cope, is an elimination reaction of an amine oxide to form an alkene and a hydroxyl amine. This organic reaction is an alternative to the Hofmann elimination with the base part of the leaving group and with a 5-membered cyclic transition state leading to syn elimination. The Cope reaction should not to be confused with the Cope rearrangement. The amine oxide is prepared by oxidation of the corresponding amine with an oxidant such as mCPBA. The actual elimination just requires heat.

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Piperidines are resistant to an intramolecular Cope reaction ^[1] but with larger rings the reaction product is an unsaturated hydroxyl amine. This result demonstrates the geometric constraints of a 5-membered cyclic transition state.

References

1. ^  Amine Oxides. VII. The Thermal Decomposition of the N-Oxides of N-Methylazacycloalkanes Arthur C. Cope, Norman A. LeBel; J. Am. Chem. Soc.; 1960; 82(17); 4656-4662. Abstract