Baylis–Hillman reaction

In organic chemistry, the Baylis–Hillman, Morita–Baylis–Hillman, or MBH reaction is a carbon–carbon bond-forming reaction between an activated alkene and a carbon electrophile in the presence of a nucleophilic catalyst, such as a tertiary amine or phosphine. The product is densely functionalized, joining the alkene at the α-position to a reduced form of the electrophile (e.g. in the case of an aldehyde, an allylic alcohol).

The reaction is named for Anthony B. Baylis and Melville E. D. Hillman, two of the chemists who developed the reaction at Celanese; and K. Morita, who published earlier work on the same.

The MBH reaction offers several advantages in organic synthesis:

1. It combines easily prepared starting materials with high atom economy.
2. It requires only mild conditions and does not require any transition metals.
3. Asymmetric synthesis is possible from prochiral electrophiles.
4. The product's dense functionalization enables many further transformations.

Its disadvantage is that the reaction is extremely slow.