Nicholas reaction
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The Nicholas reaction is an organic reaction where a dicobalt octacarbonyl-stabilized propargylic cation is reacted with a nucleophile. Oxidative demetallation gives the desired alkylated alkyne.[1][2]
Several reviews have been published.[3][4]
[edit] Reaction mechanism
The addition of dicobalt octacarbonyl to a propargylic ether (1) gives the dicobalt intermediate 2. Reaction with HBF4 or Lewis acid gives the key dicobalt octacarbonyl-stabilized propargylic cation (3a and 3b). Addition of a nucleophile followed by a mild oxidation gives the desired substituted alkyne (5).
[edit] References
- ^ Lockwood, R. F.; Nicholas, K. M. Tetrahedron Lett. 1977, 4163. (doi:10.1016/S0040-4039(01)83455-9)
- ^ Nicholas, K.M. J. Organomet. Chem. 1979, C21, 44.
- ^ Nicholas, K. M. Acc. Chem. Res. 1987, 20, 207-214. (Review) (doi:10.1021/ar00138a001)
- ^ Teobald, B. J. Tetrahedron 2002, 58, 4133-4170. (Review) (doi:10.1016/S0040-4020(02)00315-0)
