Conjugate addition organometallics, mechanism

In the last chapter we introduced the Heck reaction as a way to add nucleophiles to electrophilic alkenes. The details of the mechanism are discussed there. The reaction also occurs with allylic alcohols 218 and is a good way to make carbonyl compounds, particularly aldehydes, 219 as the alternative conjugate addition of an organometallic compound to an enal often shows poor regioselectivity (chapter 9). 

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