Asymmetric Michael Addition Reaction under the Control of the Evans Chiral Auxiliary (Ⅱ)

Chiral auxiliaries controlled asymmetric reaction is one of the main methods in asymmetric synthesis.Under the control of the Evans auxiliary and catalyzed by FeCl 3 , different Grignard reagents were added asymmetrically to the substrates 1 by the way of 1,4-Michael addition reaction, and a series of Michael addition products 2a～2h which containing two chiral centers have been synthesized with higher stereoselectivity.Among them, compounds 2d and 2e achieved high diastereospecifically up to 98% de.The results showed that the steric hindrance of the Grignard reagents is the main factor which influences the stereoselectivity of Micheal addition.