Amines: 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 alkyl halide has been converted into an alkene; however, the alkene formed is the the least highly substituted of the two possibilities. Alkenes with this regiochemistry can be formed by a Hofman elimination from a quarternary ammonium salt by treatment with silver oxide. The starting alkyl halide can be converted into the amine by a simple substitution reaction, and the primary amine can be exhaustively methylated to give the required salt. First, give the structure of the required primary amine.
The quarternary ammonium salt can be prepared by exhaustive methylation of the simple amine using excess iodomethane. This undergoes elimination in the presence of silver oxide to give the least substituted alkene. Next, give the conditions necessary for the conversion of the starting material to the intermediate primary amine.
(2-bromopropyl)benzene is reacted with azide anion to give the intermediate alkyl azide, which is immediately reduced with LiAlH4 to give the corresponding primary amine. This undergoes exhaustive methylation to give an intermediate quarternary ammonium salt, which undergoes Hofman elimination on treatment with silver oxide to give the desired compound.
