Question

In Michael Addition on alpha, beta unsaturated carbonyl compounds do Grignard Reagents undergo 1,4 or 1,2 addition?
Eg :
Ph-CH=CH-CO-Ph + Ph-MgBr + (H+) ---> ?

Answer 1

grignards are hard nucleophiles, it will attack the C=O carbon (1,2). If you use a \(Cu^+\) catalyst it will do a conjugate (1,4) attack .