A retrosynthesis using classic disconnection approach ideas from organic chemistry work out how to make this target molecule. The key steps involve reductive amination, FriedelCrafts acylation, and full carbonyl reduction.

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The main functional group that this molecule has is an amine, which is a good place to start with making disconnections in a retrosynthetic analysis. The key reaction in organic chemistry that can be used is a reductive amination mechanism. This mechanism is when you do a condensation reaction between an amine and a carbonyl compound a ketone or an aldehyde to form an imine or inimium ion. In the presence of a suitable reducing agent, the imine or iminium ion can be reduced to an amine. The options would be to have something like sodium cyanoborohydride (NaBH3CN) added to a reaction flask while the imine condensation equilibrium is being set up. Alternatively, you could use dehydrating reaction conditions for the condensation, and then subsequently treat the imine with any hydride reducing agent or even hydrogenation conditions of hydrogen gas in combination with a metal catalyst.

The next task in the retrosynthesis is to work out how to add substituents to the benzene ring. A good method for CC bond formation in this context is to use a FriedelCrafts acylation. FriedelCrafts alkylation reactions are a bit unreliable due to possible carbocation rearrangements, but also impossible in this retrosynthesis as the reaction would have to go via a primary carbocation, which are not ever an observed intermediate in solution under organic chemistry lab conditions. The FriedelCrafts acylation goes via an acylium ion intermediate instead.

The final disconnections take this retrosynthesis back to anisole (methoxybenzene), which has a good paradirecting substituent for reactions of benzene with powerful electrophiles such as acylium ions. To key everything selective, a functional group interconversion is used in the retrosynthesis to install a carbonyl group (a ketone) to use as a strategic handle for reactivity. In the forward synthesis, this carbonyl can be completely removed by full reduction to the alkyl chain. Reactions that do this include the Clemmensen reduction (Zn, HCl) and the WolffKishner reduction (NH2NH2, KOH), amongst many other possible alternatives. Using this disconnection means that succinic anhydride can be used in one of the FriedelCrafts acylation reactions, instead of the usual acid chloride, and this is a cheap and readily available symmetrical starting material.