Enols and Enolates

Conjugate Additions to a,b-Unsaturated Carbonyls 

• Michael addition - conjugate addition of enolate anion to a,b-unsaturated carbonyl

 

• Robinson annulation - cyclization of Michael adduct via internal aldol condensation

Problem: How might you use methyl vinyl ketone to add the C ring to the product of the Robinson annulation shown above? Where else in the A a or B ring can an enolate form. What would be the product of the reaction with methyl vinyl ketone at the other enolate site? The steroidal ring system is shown below.

• Generation of MVK in situ