Carbonyl a-Substitution Reactions: Multi-Step Synthesis
Suggest a synthetic scheme for the conversion shown on the left using the starting material indicated. Work each problem backwards, and draw the structures of the intermediate required for the conversion, and the reaction conditions necessary for each step.Click the mouse on the buttons to view the synthetic logic, the structure of the intermediate and the solution to the problem.
Click the mouse on the molecule to reset this frame.
Working backwards, the ketone has been converted into an a-b-unsaturated ketone. This can be done with a simple elimination reaction from an a-bromo ketone, or by direct reaction with benzeneselenyl bromide followed by work-up with H2O2. Utilizing the elimination route, draw the structure of the intermediate a-bromo ketone and the conditions necessary for the elimination.
The ketone has been converted into an a-b-unsaturated ketone. This can be done with a simple elimination reaction from an a-bromo ketone as shown here, or by direct reaction with benzeneselenyl bromide followed by work-up with H2O2. Next, give the conditions necessary for the conversion of the ketone to the intermediate a-bromo ketone.
1-Phenyl-1-propanone is reacted with bromine in acetic acid to give the a-bromo ketone. This undergoes elimination on treatment with pyridine to give the desired compound.