Overman Rearrangement

26 March, 2015 / by SK / in Reactions

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General Characteristics

The trichloroacetimidates of allylic alcohols, prepared using trichloroacetonitrile, undergo thermal or catalyzed [3,3]-sigmatropic rearrangement, which is referred to as the Overman rearrangement. This reaction is an effective option to prepare allylic amines including synthetically challenging α-quaternary amines.

General References
Overman, L. E. J. Am. Chem. Soc. 1974, 96, 597. DOI: 10.1021/ja00809a054
Overman, L. E. J. Am. Chem. Soc. 1976, 98, 2901. DOI: 10.1021/ja00426a038
Overman, L. E. Acc. Chem. Res. 1980, 13, 218. DOI: 10.1021/ar50151a005
Nishikawa, T.; Asai, M.; Ohyabu, N.; Isobe, M. J. Org. Chem.1998, 63, 188. DOI: 10.1021/jo9713924
Reaction Mechanism

The rearrangement is believed to go through a six-membered chair transition state similar to the Claisen and other rearrangements.

Examples

An application in the total synthesis of pancratistatin.^[1]

The COP (cobalt oxazoline palladacycle) catalyst was used to render the rearrangement enantioselective.^[2]

Experimental Procedure
Experimental Tips
References

[1] Danishefsky, S. J.; Lee, J. Y. J. Am. Chem. Soc. 1989, 111, 4829. DOI: 10.1021/ja00195a039
[2] (a) Anderson, C. E.; Overman, L. E. J. Am. Chem. Soc. 2003, 125, 12412. DOI: 10.1021/ja037086r
(b) Anderson, C. E.; Overman, L. E. Org. Synth. 2005, 82, 134. [website]